Fertility in the United States: Hanging On?

Key Points

  • The baby bust of the 1960s saw the U.S. total fertility rate (TFR) dip to just below the 2.1 live births per woman needed to prevent population decline.
  • U.S. TFR fell again after the Great Recession of 2008-09, which eroded women’s and couples’ economic ability to bear and raise children.
  • Large and persistent declines in European fertility to well below the 2.1 threshold is a worrisome precursor: America’s budget problem of funding elder-care would worsen if the U.S. TFR meets with the same fate as that of Europe.

Fertility in the United States: Hanging On?

Introduction

Throughout Europe, programs to provide generous maternity leave, child subsidies, public pre- and post-natal health benefits and “children’s allowance” policies have been introduced to promote childbirth. The United States also encourages procreation via similar but, thus far, indirect and less generous fiscal inducements.

Such “population policies” are increasingly the norm among developed nations – a response to the reverse fertility tsunami that has hit them. Low and declining fertility obviously means fewer and smaller families and lesser fulfillment derived from parenthood. As policymakers across the developed world recognize, however, low and declining fertility holds ominous long term economic implications.

A large and growing cadre of youths provides the wellspring of energy, activity, and vitality, generating impulses that are crucial for economic growth and prosperity. In contrast, low fertility and population decline means population aging, a diminishing revenue base for funding essential public services, and a slowdown in inventions and innovations that boost economic growth.

The degenerative effects of fertility declines extend to social and political systems as well. Slow or no economic growth makes political accommodation of rival economic interests more difficult. Systems of governance, no matter how well-crafted, become difficult to sustain without steady replenishment of human endeavor and commitment from new generations. Young generations man national defense systems, supply a pool of productive labor, advance existing productive technologies, and innovate to create jobs and improve the welfare of all citizens.

Thus, fertility declines of the magnitude experienced by European nations are concerning because they foreshadow economic decline. Will a similar fertility decline occur in the Unites States as well?

Secular Change in U.S. TFR

Fertility declined steadily in the Unites States for two centuries until the 1940s. Figure 1 shows the Total Fertility Rate (TFR), which is defined as the rate of completed live births per woman over her lifetime. In the early 1800s, that rate was 7.1, while today it stands at just under 2.0. Thus, today’s U.S. TFR is below the threshold rate of 2.1 required for preventing population decline (without net immigration). The threshold rate is larger than 2.0 because of infant mortality.


Figure 1: U.S. Total Fertility Rate - History (1800-2013) and SSA Projection (2014-2090)

Blue vertical bars indicate recession periods.
Source: United Nations and National Bureau of Economic Research.


U.S. fertility dropped precipitously before WWII from more than 3.0 during the early 1920s to just 2.0 by the beginning of the war. Americans chose to delay or forgo having children during the stressful economic conditions of the Great Depression and the prospect of a long war in Europe. Indeed, reduced fertility was unavoidable because almost one half of males aged 18-50 were involved in the war effort, with many stationed abroad.

The prewar fertility decline was reversed after WWII, however. Those who had postponed childbirth during previous decades sought to catch up and their fertility resumption coincided with childbearing by younger couples. The lighter, brighter postwar mood, surging economic opportunities, and rapid employment growth also helped: Buoyant infrastructure, home construction, and export sectors and increased business startups created a secure economic environment conducive to family formation. Innovations in consumer goods and labor-saving appliances made housework easier and raising children less onerous. The U.S. TFR skyrocketed back to pre-Great-Depression levels, reaching 3.6 by the late 1950s.

But the postwar fertility boom turned out to be temporary. America’s TFR declined again during the 1960s. The effects of two recessions during the 1960s, the stressful environment of the Cold War, and the lengthening shadow of the Vietnam War on the nation’s youth probably contributed to the end of the post WWII baby boom.

By then, the almost twenty-year boom-bust fertility cycle had produced a 78 million strong bulge in the U.S. age distribution, one that continues to grow older. The boomers made hugely significant productive contributions during their working careers – computers, the internet, space exploration, life-saving medical techniques and devices, gene-therapies, pharmaceuticals, and numerous others. Now, however, boomer retirements appear likely to pose multiple economic challenges: Ensuring adequate support for an aging boomer cohort without harming the economic prospects of younger and future generations by maintaining strong economic growth and sound government finances.

Recent Developments in U.S. Fertility

The lowest TFR in U.S. recorded history occurred during the 1970s – years that were again marked by recession, heightened Cold War fears, and an oil supply crisis. The historically lowest TFR of 1.74 was registered in 1976. Although the TFR recovered a bit during the 1980s, it has surpassed the critical value of 2.1 in only two years, both occurring during the economic expansion that preceded the Great Recession of 2008-2009.

An interesting feature of the U.S. TFR is the correlation between business cycle downturns, indicated in Figure 1 by blue vertical bars, and declines in the TFR. Calculations based on changes in the TFR during and after recessions since the 1960s show that the average cumulative decline in TFR four years after a business cycle peak equals 7 percent. Research shows that economic adversity reduces social engagement – dating and marriage – and increases anti-natal actions including pregnancy terminations.

Many analysts express relief that after its two-decade-long decline through the 1970s, the U.S. TFR has remained relatively steady at just below 2.0 since the late 1980s. However, what is truly noteworthy is that the TFR did not increase during that period – a time of the “Great Moderation” marked by declining inflation and revival of economic growth. It means that although fertility is clearly adversely affected during economic recessions, it does not register the opposite response during times of economic stability or prosperity. That U.S. fertility remained essentially flat during the roughly two decades of relative social and political stability since 1990 (until just before the onset of the Great Recession in 2008-2009) is not good news.


Figure 2: U.S. Total Fertility Rate - Recent History and Short-Term Projections

Source: Social Security Administration.


This suggests that several other anti-natal changes have accrued during recent decades. Those include social mores about marriage and childbearing and growing educational and employment opportunities for women that compete with fertility and family-formation options. These changes affect the trade-off between investing in one’s own productive and earning abilities versus investing in family formation. The recent flat trajectory of U.S. TFR close to 2.0 suggests that to be the “equilibrium” outcome from the balance of two forces – a quiescent, pro-natal environment with steady economic growth versus anti-natal changes in social norms, economic incentives, and labor market opportunities for women.

Figure 2 focuses on U.S. fertility over the years since the onset of the Great Recession. A sizable drop in the TFR from 2008 through 2012 again underscores the relationship between the economy and personal decisions to have children. The Great Recession, which began in late 2007, provoked a larger-than-average decline in fertility, which fell by 11 percent to less than 1.9 in 2011 from the high of 2.1 in 2007. The economic collapse in financial and business sectors had a ripple effect on the pocketbooks of middle-class Americans who suffered massive job losses, mortgage failures, and asset devaluations. An austere financial outlook prompted many to postpone or forgo fertility out of economic necessity.

The U.S. Social Security Administration projects an increase in U.S. TFR during the next few years as the economy recovers. However, the timing and magnitude of any such recovery remain highly uncertain. The aforementioned anti-natal forces – greater educational and labor-market opportunities for women continue to compete directly – and more intensely as returns to education have skyrocketed – with the traditional norms of procreation and family formation. These changes are reflected in continuing gains in female representation and achievements in education and in the labor force, lower incidence of marriages, and higher incidence of divorce. True, reduced prevalence of dual-headed families has been partly offset by higher prevalence of single-headed ones. But the increased prevalence of younger single individuals – who appear to be postponing or rejecting marriage and family formation – means that overall rates of family formation are likely to remain depressed. Hence, concern about the future course of U.S. TFR remains high, notwithstanding an incipient economic recovery from the Great Recession.

Whither TFR Recovery?

Concern about a recovery in U.S. TFR is also prompted by two other observations: First, persistently low fertility in the developed nations of Europe, Japan, and Australia raises concerns that those nations’ low fertility rates are indicative of what’s in store for the United States. Second, recent U.S. gains in human longevity have occurred at a faster pace than expected. The continuation of this unexpected increase would mean that the financial burden of funding social insurance benefits of retired generations would rest on younger taxpayers. In turn, a heavier tax burden would make it more difficult for young couples to contemplate having and rearing children.

Other Developed Nations

European and other developed nations, who share many social and cultural values with Americans, are collectively experiencing what can only be described as a fertility implosion. The decline in fertility has been so drastic that serious efforts aimed at increasing family formation and encouraging procreation have been on the rise.

  • The sex education curriculum in some European schools has shifted focus from teaching teens about pregnancy prevention to encouraging them to have babies when they become adults.
  • Danish travel company launched a campaign entitled, "Do It for Denmark" that enticed couples to book romantic getaways in order to "save" Denmark's future.1

Figure 3 provides a comparison of fertility rates in various European nations, Japan and Australia. The post WWII declines in TFRs progressed to levels well below the replacement level of 2.1 per woman in many European nations with similar social traditions, economic productivity levels, and democratic political institutions as in the United States. In Greece, Spain, and Italy, for example, the TFR bottomed out in the mid-1980s at just above 1.1 percent – almost one-half of the TFR required for population replacement. It rose again during the first decade of this century but the recent continent-wide economic recession appears to have induced yet another TFR decline. These developments motivate the renewed encouragement and policy initiatives in Europe to increase procreation and family formation by younger generations.

But a key question is whether America’s TFR will follow in the footsteps of Europe, Japan, and Australia. In the European tug-of-war between pro and anti-natal forces, the latter appear to be winning. An important characteristic of fertility declines in European and other developed nations is that large fertility reductions have occurred over a short time span – as little as a decade. And public policy initiatives toward recovering fertility rates have remained mostly ineffective thus far.


Figure 3: Fertility Declines in Europe, Japan, and Australia – Sudden … and Permanent?

Source: Eurostat and United Nations.


Increases in Longevity

The pace of gains in human longevity is also highly uncertain. Uncertainty about future longevity increases arises from different factors compared to fertility. Uncertainty about the latter arises from unknown factors that influence young individuals’ decisions regarding procreation and family formation. Uncertainty about improvements in human longevity arises from unknown future changes in medical and public health technologies and practices. As Figure 4 shows, recent projections of the reductions in deaths per 100,000 individuals among those aged 65 and older tell the story quite clearly: In the span of just over a decade, the cumulative reduction in the death rate has been almost 20 percent. And actual reductions in deaths have consistently exceeded the best projections made by demographers, as Figure 4 also indicates. With continued progress in finding cures for many diseases that posed challenges earlier, medical practitioners appear to be on the verge of a revolution in curing cancer, neurological diseases, and other ailments that are the major causes of death today. Consequently, government programs for supporting the elderly may be much less financially viable than we believe today based on today’s mortality projections.

What are the implications for fertility? Longer and healthier lifetimes, considered a positive development from a human welfare perspective can imply an even greater need for sustaining population growth. A recovery of U.S. fertiity to pre-WWII levels would go a long way toward ensuring long-term sustainability for programs that fund consumption and health care for a progressively older population. If the financial burden of forthcoming increases in elder-care expenses falls mainly on today's younger working generations, the tax imperatives of elder-care will likely crowd out childbirth and family formation.


Figure 4: Actual and Projected Deaths/100,000 People Aged 65 and Older

Source: Social Security Trustees' Reports (various years).


Thus, a pro-growth economic policy that encourages pre-funding one’s own retirement security appears to be an essential complement to other fiscal incentive programs for encouraging procreation and family formation by the young. Such measures are becoming the norm in many of the nations that are facing the twin challenges for funding retirement security for aging populations and low or declining fertility. Policymakers in these countries are also learning that continuity of a pro-natal policy stance is very important. For the young to undertake the long-term efforts and commitments of procreation, creating and preserving the expectation of secure sources of economic support is a key and necessary component.

Hanging On?

The dip in the U.S. TFR after the Great Recession was significant. Although a recovery is still expected, it remains quite uncertain. Younger generations’ and especially younger women’s fertility decisions are sensitive to their perception of future economic prospects but also to alternative opportunities today to acquire education, work, and remain economically self-sufficient and independent. The U.S. TFR remains just below the replacement level of 2.1 – an “equilibrium” between the push of a stable social environment and improving economy and pull of changes in social norms about marriage and family formation and incentives and opportunities that compete with family formation. Whether U.S. TFR will continue at its current level or suffer a European fate depends on the interplay of those forces.

Most analysts believe that a declining population is a harbinger of slower economic growth. However, an ominous future addition to the forces promoting population decline is the rapid prospective growth of entitlement benefits to retiring boomers. As persistent low fertility adds to the challenge of maintaining strong economic growth and sound government finances, boomer retirements and their increasing longevity also appear likely to propel upward tax burdens on younger generations, compounding the policy challenge of recovering from low fertility.

Conclusion

The recovery of U.S. fertility will become more difficult if economic recovery stalls with poor job opportunities, limited labor mobility, an unsettled social environment, war, and growing tax burdens on younger generations for supporting retired ones. Creating a stable pro-natal and pro-family environment requires the opposite: Peacetime, ample job opportunities, low taxes to make family formation affordable, and especially for women, opportunities to re-enter the labor force after temporary exits for childbearing – all being elements of a pro-growth policy and economic environment.


  1. Danish travel company, Spies, offers romantic holidays in order to “save” Denmark’s future. For more information see: http://www.spies.dk/do-it-for-denmark  ↩

Year,Albania,Andorra,Armenia,*Australia,Austria,Belarus,Belgium,Bulgaria,Croatia,Cyprus,Czech Republic,Denmark,Estonia,Finland,*France,*Germany (including former GDR),Greece,Hungary,Iceland,Ireland,Italy,*Japan,Latvia,Liechtenstein,Lithuania,Luxembourg,Malta,Moldova,Montenegro,Netherlands,Norway,Poland,Portugal,Romania,Russia,San Marino,Serbia,Slovakia,Slovenia,Spain,Sweden,Switzerland,Turkey,Ukraine,United Kingdom
1960,,,,3.451,2.7,,2.5,2.3,,,2.1,2.6,2,2.7,2.8,2.4,2.2,2,,3.8,2.4,2.001,,,,2.3,,,,3.1,,,3.2,,,,,3,,,,2.4,,,
1961,,,,3.548,2.8,,2.6,2.3,,,2.1,2.6,2,2.7,2.8,2.4,2.1,1.9,,3.8,2.4,1.976,,,,,,,,3.2,2.9,,3.2,,,,,3,,,,2.5,,,
1962,,,,3.431,2.8,,2.6,2.2,,,2.1,2.5,2,2.7,2.8,2.5,2.2,1.8,,3.9,2.4,1.965,,,,,,,,3.2,2.9,,3.2,,,,,2.8,,,,2.6,,,
1963,,,,3.343,2.8,,2.7,2.2,,,2.3,2.7,1.9,2.7,2.8,2.5,2.1,1.8,4,4,2.5,1.965,,,,,,,,3.2,2.9,,3.1,,,,,2.9,,,,2.6,,,
1964,,,,3.154,2.8,,2.7,2.2,,,2.3,2.6,1.9,2.6,2.8,2.5,2.2,1.8,3.9,4.1,2.7,1.97,,,,,,,,3.2,3,,3.2,,,,,2.9,,,,2.7,,,
1965,,,,2.973,2.7,,2.6,2.1,,,2.2,2.6,1.9,2.5,2.8,2.5,2.2,1.8,3.7,4,2.6,1.98,,,,,,,,3,2.9,,3.1,,,,,2.8,,,,2.6,,,
1966,,,,2.885,2.7,,2.5,2,,,2,2.6,1.9,2.4,2.7,2.4,2.3,1.9,3.6,3.9,2.6,1.997,,,,,,,,2.9,2.9,,3.2,,,,,2.7,,,,2.5,,,
1967,,,,2.847,2.6,,2.4,2,,,1.9,2.4,1.9,2.3,2.7,2.4,2.4,2,3.3,3.8,2.5,2.02,,,,2.2,,,,2.8,2.8,,3.2,,,,,2.5,,,,2.4,,,
1968,,,,2.886,2.6,,2.3,2.3,,,1.8,2.1,2,2.1,2.6,2.3,2.4,2.1,3.1,3.8,2.5,2.048,,,,2.1,,,,2.7,2.8,,3.1,,,,,2.4,,,2.1,2.3,,,
1969,,,,2.887,2.5,,2.3,2.3,,,1.9,2,2.1,1.9,2.6,2.2,2.4,2,3,3.8,2.5,2.077,,,,2,,,,2.7,2.7,,3.1,,,,,2.4,,,1.9,2.2,,,
1970,,,,2.859,2.3,,2.3,2.2,,,1.9,2,2.2,1.8,2.5,2,2.4,2,2.8,3.9,2.4,2.101,,,2.4,2,,,,2.6,2.5,,3,,,,,2.4,,,1.9,2.1,,,
1971,,,,2.945,2.2,,2.2,2.1,,,2,2,2.2,1.7,2.4,1.9,2.3,1.9,2.9,3.9,2.4,2.113,,,2.4,2,,,,2.4,2.5,,3,,,,,2.4,,2.9,2,2,,,
1972,,,,2.743,2.1,,2.1,2,,,2.1,2,2.1,1.6,2.3,1.8,2.3,1.9,3.1,3.8,2.3,2.109,,,2.3,1.7,,,,2.2,2.4,,2.9,,,,,2.5,,2.9,1.9,1.9,,,
1973,,,,2.491,1.9,,1.9,2.1,,,2.3,1.9,2.1,1.5,2.2,1.7,2.3,1.9,2.9,3.7,2.3,2.087,,,2.2,1.6,,,,1.9,2.2,,2.8,,,,,2.6,,2.8,1.9,1.8,,,2
1974,,,,2.321,1.9,,1.8,2.3,,,2.5,1.9,2.1,1.6,2.1,1.6,2.4,2.3,2.7,3.6,2.3,2.048,,,2.2,1.6,,,,1.8,2.1,,2.7,,,,,2.6,,2.9,1.9,1.7,,,1.9
1975,,,,2.148,1.8,,1.7,2.2,,,2.4,1.9,2,1.7,2.1,1.6,2.3,2.3,2.6,3.4,2.2,1.997,,,2.2,1.5,,,,1.7,2,,2.8,2.6,,,,2.5,,2.8,1.8,1.6,,,1.8
1976,,,,2.06,1.7,,1.7,2.2,,,2.4,1.7,2.1,1.7,2,1.5,2.3,2.2,2.5,3.3,2,1.94,,,2.2,1.5,,,,1.6,1.9,,2.8,2.5,,,,2.5,,2.8,1.7,1.5,,,1.7
1977,,,,2.007,1.6,,1.7,2.2,,,2.3,1.7,2.1,1.7,1.9,1.5,2.3,2.2,2.3,3.2,1.9,1.885,,,2.1,1.5,2.1,,,1.6,1.8,,2.7,2.6,,,,2.5,,2.7,1.6,1.5,,,1.7
1978,,,,1.949,1.6,,1.7,2.1,,,2.3,1.7,2,1.6,1.9,1.5,2.3,2.1,2.3,3.2,1.8,1.838,,,2.1,1.5,2.1,,,1.6,1.8,,2.5,2.5,,,,2.5,,2.5,1.6,1.5,,,1.8
1979,,,,1.907,1.6,,1.7,2.2,,,2.3,1.6,2,1.6,1.8,1.5,2.3,2,2.5,3.2,1.7,1.802,,,2,1.5,2.1,,,1.6,1.8,,2.3,2.5,,,,2.5,,2.4,1.7,1.5,,,1.9
1980,,,,1.891,1.7,,1.7,2.1,,,2.1,1.5,2,1.6,1.8,1.5,2.2,1.9,2.5,3.2,1.6,1.777,,,2,1.5,2,,,1.6,1.7,,2.3,2.4,,,,2.3,,2.2,1.7,1.6,,,1.9
1981,,,,1.935,1.7,,1.7,2,,,2,1.4,2.1,1.6,1.8,1.5,2.1,1.9,2.3,3.1,1.6,1.761,,,2,1.6,1.9,,,1.6,1.7,,2.1,2.4,,,,2.3,,2,1.6,1.5,,,1.8
1982,,,,1.929,1.7,,1.6,2,,2.5,2,1.4,2.1,1.7,1.8,1.5,2,1.8,2.3,2.9,1.6,1.751,,,2,1.5,,,,1.5,1.7,,2.1,2.2,,,,2.3,1.9,1.9,1.6,1.6,,,1.8
1983,,,,1.924,1.6,,1.6,2,,2.5,2,1.4,2.2,1.7,1.8,1.5,1.9,1.7,2.2,2.7,1.5,1.741,,,2.1,1.4,,,,1.5,1.7,,2,2.1,,,,2.3,1.8,1.8,1.6,1.5,,,1.8
1984,,,,1.84,1.5,,1.5,2,,2.5,2,1.4,2.2,1.7,1.8,1.5,1.8,1.8,2.1,2.6,1.5,1.73,,,2.1,1.4,2,,,1.5,1.7,,1.9,2.3,,,,2.3,1.7,1.7,1.7,1.5,,,1.8
1985,,,,1.923,1.5,,1.5,2,,2.4,2,1.4,2.1,1.6,1.8,1.5,1.7,1.8,1.9,2.5,1.4,1.715,,,2.1,1.4,1.9,,,1.5,1.7,,1.7,2.3,,,,2.3,1.7,1.6,1.7,1.5,,,1.8
1986,,,,1.868,1.4,,1.5,2,,2.5,1.9,1.5,2.2,1.6,1.8,1.4,1.6,1.8,1.9,2.4,1.4,1.695,,,2.1,1.4,1.9,,,1.6,1.7,,1.7,2.4,,,,2.2,1.7,1.6,1.8,1.5,,,1.8
1987,,,,1.845,1.4,,1.5,2,,2.4,1.9,1.5,2.3,1.6,1.8,1.4,1.5,1.8,2.1,2.3,1.3,1.67,,,2.1,1.4,2,,,1.6,1.7,,1.6,2.4,,,,2.1,1.6,1.5,1.8,1.5,,,1.8
1988,,,,1.831,1.4,,1.6,2,,2.5,1.9,1.6,2.3,1.7,1.8,1.4,1.5,1.8,2.3,2.2,1.4,1.641,,,2,1.5,2.1,,,1.5,1.8,,1.6,2.3,,,,2.1,1.6,1.5,2,1.6,,,1.8
1989,,,,1.838,1.4,,1.6,1.9,,2.4,1.9,1.6,2.2,1.7,1.8,1.4,1.4,1.8,2.2,2.1,1.3,1.607,,,2,1.5,2.1,,,1.6,1.9,,1.6,2.2,,,,2.1,1.5,1.4,2,1.6,,,1.8
1990,,,,1.902,1.5,,1.6,1.8,,2.4,1.9,1.7,2,1.8,1.8,1.4,1.4,1.9,2.3,2.1,1.3,1.571,,,2,1.6,2,,,1.6,1.9,2.1,1.6,1.8,,,,2.1,1.5,1.4,2.1,1.6,,,1.8
1991,,,,1.849,1.5,,1.7,1.7,,2.3,1.9,1.7,1.8,1.8,1.7,1.3,1.4,1.9,2.2,2.1,1.3,1.535,,,2,1.6,2,,,1.6,1.9,2.1,1.6,1.6,,,,2,1.4,1.3,2.1,1.6,,,1.8
1992,,,,1.888,1.5,,1.6,1.5,,2.5,1.7,1.8,1.7,1.8,1.7,1.3,1.4,1.8,2.2,2,1.3,1.499,,,2,1.6,2.1,,,1.6,1.9,2,1.5,1.5,,,,1.9,1.3,1.3,2.1,1.6,,,1.8
1993,,,,1.859,1.5,,1.6,1.5,,2.2,1.7,1.7,1.5,1.8,1.7,1.3,1.3,1.7,2.2,1.9,1.3,1.467,,,1.7,1.7,2,,,1.6,1.9,1.9,1.5,1.4,,,,1.9,1.3,1.3,2,1.5,,,1.8
1994,,,,1.842,1.5,,1.6,1.4,,2.2,1.4,1.8,1.4,1.8,1.7,1.3,1.4,1.6,2.1,1.8,1.2,1.438,,,1.6,1.7,1.9,,,1.6,1.9,1.8,1.4,1.4,,,,1.7,1.3,1.2,1.9,1.5,,,1.7
1995,,,,1.822,1.4,,1.6,1.2,,2,1.3,1.8,1.4,1.8,1.7,1.3,1.3,1.6,2.1,1.8,1.2,1.413,,,1.6,1.7,1.8,,,1.5,1.9,1.6,1.4,1.3,,,,1.5,1.3,1.2,1.7,1.5,,,1.7
1996,,,,1.796,1.4,,1.6,1.2,,2,1.2,1.7,1.4,1.8,1.7,1.3,1.3,1.5,2.1,1.9,1.2,1.392,,,1.5,1.8,2,,,1.5,1.9,1.6,1.4,1.3,,,,1.5,1.3,1.2,1.6,1.5,,,1.7
1997,,,,1.778,1.4,,1.6,1.1,,1.9,1.2,1.8,1.3,1.7,1.8,1.3,1.3,1.4,2,1.9,1.2,1.372,,,1.5,1.7,2,,,1.6,1.9,1.5,1.5,1.3,,,,1.4,1.2,1.2,1.5,1.5,,,1.7
1998,,,,1.762,1.4,,1.6,1.1,,1.8,1.2,1.7,1.3,1.7,1.8,1.3,1.3,1.3,2,1.9,1.2,1.354,,,1.5,1.7,1.9,,,1.6,1.8,1.4,1.5,1.3,,,,1.4,1.2,1.2,1.5,1.5,,,1.7
1999,,,,1.755,1.3,,1.6,1.2,,1.7,1.1,1.7,1.3,1.7,1.8,1.3,1.2,1.3,2,1.9,1.2,1.337,,,1.5,1.7,1.8,,,1.7,1.8,1.4,1.5,1.3,,,,1.3,1.2,1.2,1.5,1.5,,,1.7
2000,,,,1.756,1.4,,1.7,1.3,,1.6,1.1,1.8,1.4,1.7,1.8,1.4,1.3,1.3,2.1,1.9,1.3,1.322,1.2,1.6,1.4,1.8,1.7,,,1.7,1.9,1.4,1.5,1.3,,,1.5,1.3,1.3,1.2,1.5,1.5,,,1.6
2001,,,,1.729,1.3,,1.7,1.2,1.5,1.6,1.1,1.7,1.3,1.7,1.8,1.4,1.3,1.3,2,1.9,1.3,1.31,1.2,1.5,1.3,1.7,1.5,,,1.7,1.8,1.3,1.4,1.3,,,1.6,1.2,1.2,1.2,1.6,1.4,,,1.6
2002,,,,1.756,1.4,,1.6,1.2,1.4,1.5,1.2,1.7,1.4,1.7,1.9,1.4,1.3,1.3,1.9,2,1.3,1.303,1.3,1.5,1.2,1.6,1.5,,,1.7,1.8,1.2,1.5,1.3,,,1.6,1.2,1.2,1.3,1.6,1.4,,,1.6
2003,,,,1.748,1.4,,1.7,1.3,1.4,1.5,1.2,1.8,1.4,1.8,1.9,1.4,1.3,1.3,2,2,1.3,1.3,1.3,1.4,1.3,1.6,1.5,,,1.7,1.8,1.2,1.4,1.3,,,1.6,1.2,1.2,1.3,1.7,1.4,,,1.7
2004,1.8,,,1.763,1.4,,1.7,1.3,1.4,1.5,1.2,1.8,1.5,1.8,1.9,1.4,1.3,1.3,2,1.9,1.3,1.301,1.3,1.4,1.3,1.7,1.4,,,1.7,1.8,1.2,1.4,1.3,,,1.6,1.2,1.2,1.3,1.8,1.4,,,1.8
2005,1.6,,,1.791,1.4,,1.8,1.4,1.5,1.5,1.3,1.8,1.5,1.8,1.9,1.4,1.3,1.3,2,1.9,1.3,1.307,1.4,1.5,1.3,1.6,1.4,,1.7,1.7,1.8,1.2,1.4,1.4,,,1.4,1.3,1.3,1.3,1.8,1.4,,,1.8
2006,1.4,1.2,1.3,1.817,1.4,1.3,1.8,1.4,1.5,1.5,1.3,1.8,1.6,1.8,2,1.4,1.4,1.3,2.1,1.9,1.4,1.317,1.5,1.4,1.3,1.6,1.4,1.2,1.7,1.7,1.9,1.3,1.4,1.4,1.3,,1.4,1.3,1.3,1.4,1.9,1.4,,1.3,1.8
2007,,1.2,1.4,1.92,1.4,1.4,1.8,1.5,1.5,1.4,1.4,1.8,1.7,1.8,2,1.4,1.4,1.3,2.1,2,1.4,1.329,1.5,1.4,1.4,1.6,1.4,1.2,1.8,1.7,1.9,1.3,1.3,1.4,1.4,,1.4,1.3,1.4,1.4,1.9,1.5,,1.3,1.9
2008,,1.3,1.4,1.956,1.4,1.4,1.9,1.6,1.6,1.5,1.5,1.9,1.7,1.8,2,1.4,1.5,1.3,2.2,2.1,1.4,1.343,1.6,1.4,1.4,1.6,1.4,1.3,1.9,1.8,2,1.4,1.4,1.6,1.5,,1.4,1.3,1.5,1.4,1.9,1.5,2.1,1.4,1.9
2009,,1.2,1.5,1.903,1.4,,1.8,1.7,1.6,1.5,1.5,1.8,1.7,1.9,2,1.4,1.5,1.3,2.2,2.1,1.4,1.359,1.5,1.7,1.5,1.6,1.4,1.3,2,1.8,2,1.4,1.3,1.7,1.5,,1.4,1.4,1.5,1.4,1.9,1.5,2.1,,1.9
2010,,1.3,,1.886,1.4,,1.9,1.6,1.5,1.4,1.5,1.9,1.7,1.9,2,1.4,1.5,1.2,2.2,2,1.5,1.374,1.4,1.4,1.5,1.6,1.4,1.3,1.7,1.8,1.9,1.4,1.4,1.6,1.6,,1.4,1.4,1.6,1.4,2,1.5,2,1.4,1.9
2011,,,,1.884,1.4,1.5,1.8,1.5,1.5,1.3,1.4,1.8,1.6,1.8,2,1.4,1.4,1.2,2,2,1.4,1.389,1.3,1.7,1.6,1.5,1.5,1.3,1.7,1.8,1.9,1.3,1.3,1.5,,,1.4,1.4,1.6,1.3,1.9,1.5,2,1.5,1.9
2012,,,,1.887,1.4,1.6,1.8,1.5,1.5,1.4,1.5,1.7,1.6,1.8,2,1.4,1.3,1.3,2,2,1.4,1.405,1.4,1.5,1.6,1.6,1.4,1.3,1.7,1.7,1.9,1.3,1.3,1.5,,1.3,1.4,1.3,1.6,1.3,1.9,1.5,2.1,1.5,1.9
2013,,,,1.882,1.4,,1.8,1.5,1.5,1.3,1.5,1.7,1.5,1.7,2,1.4,1.3,1.4,1.9,2,1.4,1.419,1.5,1.5,1.6,1.5,1.4,,1.7,1.7,1.8,1.3,1.2,1.4,,,1.4,1.3,1.5,1.3,1.9,1.5,2.1,,1.8