Year | Value | 2021 | 2.7040382134131 | 2020 | 2.7065676599366 | 2019 | 2.6958920168505 | 2018 | 2.7013376863832 | 2017 | 2.6980277878961 | 2016 | 2.6938860821404 | 2015 | 2.7000413756429 | 2014 | 2.7026523658753 | 2013 | 2.7035900453918 | 2012 | 2.7181829133401 | 2011 | 2.7351578670697 | 2010 | 2.7540493478332 | 2009 | 2.7769381564105 | 2008 | 2.8057955777508 | 2007 | 2.8255084272432 | 2006 | 2.8337221145317 | 2005 | 2.8364600102945 | 2004 | 2.8474115933458 | 2003 | 2.8474115933458 | 2002 | 2.8638389679228 | 2001 | 2.8665768636856 | 2000 | 2.8528873848715 | 1999 | 2.8419358018202 | 1998 | 2.8665768636856 | 1997 | 2.8419358018202 | 1996 | 3.0992980035264 | 1995 | 3.0856085247122 | 1994 | 2.8200326357175 | 1993 | 2.7734884077493 | 1992 | 2.746109450121 | 1991 | 2.7652747204608 | 1990 | 2.6721862645245 | 1989 | 2.713254700967 | 1988 | 2.6721862645245 | 1987 | 2.6557588899475 | 1986 | 2.6530209941847 | 1985 | 2.6201662450307 | 1984 | 2.6119525577422 | 1983 | 2.5873114958767 | 1982 | 2.5790978085882 | 1981 | 2.5626704340112 | 1980 | 2.5626704340112 | 1979 | 2.6119525577422 | 1978 | 2.4641061865493 | 1977 | 2.4613682907864 | 1976 | 2.4531546034979 | 1975 | 2.4586303950236 | 1974 | 2.4668440823121 | 1973 | 2.4750577696006 | 1972 | 2.4914851441776 | 1971 | 2.5489809551971 | 1970 | 2.6119525577422 | 1969 | 2.6995652221529 | 1968 | 2.7214683882555 | 1967 | 2.7378957628325 | 1966 | 2.7515852416467 | 1965 | 2.7680126162237 | 1964 | 2.7899157823263 | 1963 | 2.8145568441918 | 1962 | 2.8227705314803 | 1961 | 2.8309842187688 |
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