| Year | Value | | 2021 | 71.888090963495 | | 2020 | 71.888090963495 | | 2019 | 71.888090963495 | | 2018 | 71.888090963495 | | 2017 | 71.888090963495 | | 2016 | 71.888090963495 | | 2015 | 71.888090963495 | | 2014 | 71.888090963495 | | 2013 | 71.888090963495 | | 2012 | 71.888090963495 | | 2011 | 71.638739277878 | | 2010 | 71.140035906643 | | 2009 | 70.642110004504 | | 2008 | 69.637405535258 | | 2007 | 68.382463340173 | | 2006 | 67.377758870927 | | 2005 | 66.373054401682 | | 2004 | 66.373054401682 | | 2003 | 65.622341224163 | | 2002 | 64.120914869126 | | 2001 | 63.119963965767 | | 2000 | 62.619488514088 | | 1999 | 61.368299884891 | | 1998 | 61.268204794555 | | 1997 | 60.91787197838 | | 1996 | 60.91787197838 | | 1995 | 60.66763425254 | | 1994 | 60.567539162204 | | 1993 | 60.467444071868 | | 1992 | 60.317301436365 | | 1991 | 60.217206346029 | | 1990 | 59.866873529853 | | 1989 | 59.366398078174 | | 1988 | 59.141184124919 | | 1987 | 59.141184124919 | | 1986 | 59.141184124919 | | 1985 | 58.055152394775 | | 1984 | 57.554676943096 | | 1983 | 56.553726039738 | | 1982 | 54.251538962014 | | 1981 | 53.851158600671 | | 1980 | 53.450778239327 | | 1979 | 53.100445423152 | | 1978 | 53.100445423152 | | 1977 | 52.740103097943 | | 1976 | 52.740103097943 | | 1975 | 52.084480256243 | | 1974 | 51.368800360342 | | 1973 | 50.948400980932 | | 1972 | 50.548020619589 | | 1971 | 50.197687803413 | | 1970 | 49.947450077574 | | 1969 | 49.79730744207 | | 1968 | 49.67218857915 | | 1967 | 49.487012662029 | | 1966 | 49.471998398479 | | 1965 | 49.401931835244 | | 1964 | 49.411941344277 | | 1963 | 46.334017316451 | | 1962 | 45.613332666033 | | 1961 | 45.132876232421 |
|