Year | Value | 2022 | 1.4911528403068 | 2021 | 1.5030697701639 | 2020 | 1.6058846660771 | 2019 | 1.7185709672459 | 2018 | 1.7186090724527 | 2017 | 1.6982874008586 | 2016 | 1.8242312089992 | 2015 | 1.9870779153896 | 2014 | 2.0458672847055 | 2013 | 1.9797304445739 | 2012 | 1.8423776428184 | 2011 | 1.8731953082671 | 2010 | 1.9644165874656 | 2009 | 1.9236564043708 | 2008 | 1.907579552408 | 2007 | 1.9102379129554 | 2006 | 1.9274179881508 | 2005 | 1.9553498537411 | 2004 | 1.9401475799498 | 2003 | 1.7856072672175 | 2002 | 1.8120349074058 | 2001 | 1.9821354959012 | 2000 | 1.9848855441556 | 1999 | 1.978856746873 | 1998 | 2.0018685105872 | 1997 | 2.0073836803863 | 1996 | 2.031195864282 | 1995 | 2.1191184382609 | 1994 | 2.068690926408 | 1993 | 2.167123564454 | 1992 | 2.4848162133217 | 1991 | 2.7799235301078 | 1990 | 2.8687941022114 | 1989 | 2.7717287510938 | 1988 | 2.8299149967268 | 1987 | 2.977532042779 | 1986 | 3.0575997611811 | 1985 | 3.1041077520309 | 1984 | 3.1860078196917 | 1983 | 3.1439013046766 | 1982 | 3.423380854044 | 1981 | 3.4490401078202 | 1980 | 3.081610142926 | 1979 | 2.7787123195615 | 1978 | 2.707237949931 | 1977 | 3.173248355352 | 1976 | 3.2443185171814 | 1975 | 2.8880836916806 | 1974 | 2.7136418492678 | 1973 | 2.6808416126887 | 1972 | 2.6646315505467 | 1971 | 2.6850697378686 | 1970 | 2.7183850067803 | 1969 | 2.7288465052337 | 1968 | 2.7363819599705 | 1967 | 2.7406845801044 | 1966 | 2.6968304803114 | 1965 | 2.6536170090934 | 1964 | 2.6325416444833 | 1963 | 2.6018095417263 | 1962 | 2.5492940519092 | 1961 | 2.5114608349715 |
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