Year | Value | 2022 | 2.5981025883023 | 2021 | 2.6358194058604 | 2020 | 2.711853657933 | 2019 | 2.7748797807221 | 2018 | 2.7637376380325 | 2017 | 2.8337980949499 | 2016 | 2.9921754161178 | 2015 | 3.147582248969 | 2014 | 3.0355075699805 | 2013 | 2.8135383957443 | 2012 | 2.8149837824442 | 2011 | 2.8312367354185 | 2010 | 2.8512153153 | 2009 | 2.8466220049048 | 2008 | 2.8369709012497 | 2007 | 2.7806709683802 | 2006 | 2.7190343390934 | 2005 | 2.7331598125051 | 2004 | 2.7446220675013 | 2003 | 2.7291150903178 | 2002 | 2.6796659762753 | 2001 | 2.6266738765837 | 2000 | 2.6360272671936 | 1999 | 2.6497701815017 | 1998 | 2.6432803610119 | 1997 | 2.6593389034885 | 1996 | 2.7154943901913 | 1995 | 2.784354192833 | 1994 | 2.8585323046541 | 1993 | 2.9103294290957 | 1992 | 2.9357103573393 | 1991 | 2.9922555112262 | 1990 | 3.031332547493 | 1989 | 3.0177775678828 | 1988 | 3.0735270222116 | 1987 | 3.126735339108 | 1986 | 3.0976873195138 | 1985 | 3.0622875905759 | 1984 | 2.8578886935424 | 1983 | 2.1182946713714 | 1982 | 2.438446903415 | 1981 | 3.5643647201799 | 1980 | 3.2993457271106 | 1979 | 2.8310049451198 | 1978 | 2.738344106422 | 1977 | 2.5827859606679 | 1976 | 2.675785471643 | 1975 | 2.7786658348131 | 1974 | 2.7621523957437 | 1973 | 2.7408706218252 | 1972 | 2.710897074248 | 1971 | 2.6692895450594 | 1970 | 2.6150285398016 | 1969 | 2.5625111941814 | 1968 | 2.5138074784775 | 1967 | 2.4653701780094 | 1966 | 2.4219594341409 | 1965 | 2.3809321084285 | 1964 | 2.3435391691182 | 1963 | 2.304937442539 | 1962 | 1.9704382570752 | 1961 | 1.6039750102579 |
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