| Year | Value | | 2022 | 46.442472459721 | | 2021 | 46.4447825267 | | 2020 | 46.452693827395 | | 2019 | 46.449877971586 | | 2018 | 46.432382633345 | | 2017 | 46.41267100355 | | 2016 | 46.392676652377 | | 2015 | 46.373974621367 | | 2014 | 46.353735005292 | | 2013 | 46.326083536717 | | 2012 | 46.293150699924 | | 2011 | 46.26250369312 | | 2010 | 46.239655285786 | | 2009 | 46.229953787918 | | 2008 | 46.235144716503 | | 2007 | 46.252442037338 | | 2006 | 46.291421193537 | | 2005 | 46.364671266559 | | 2004 | 46.451271930553 | | 2003 | 46.532813991248 | | 2002 | 46.601514954282 | | 2001 | 46.656778964729 | | 2000 | 46.70278401817 | | 1999 | 46.730639276972 | | 1998 | 46.74178430563 | | 1997 | 46.752838374202 | | 1996 | 46.7792790655 | | 1995 | 46.822419563459 | | 1994 | 46.867086414739 | | 1993 | 46.892308368045 | | 1992 | 46.895965812907 | | 1991 | 46.884939895956 | | 1990 | 46.857067751929 | | 1989 | 46.801648724811 | | 1988 | 46.716528574614 | | 1987 | 46.615418646134 | | 1986 | 46.514524388038 | | 1985 | 46.427784544763 | | 1984 | 46.354466159718 | | 1983 | 46.285308950452 | | 1982 | 46.218892432538 | | 1981 | 46.154904848015 | | 1980 | 46.093640399192 | | 1979 | 46.040247789713 | | 1978 | 45.979389463857 | | 1977 | 45.900988702051 | | 1976 | 45.826260932203 | | 1975 | 45.762851201644 | | 1974 | 45.705317383954 | | 1973 | 45.647261611124 | | 1972 | 45.589264610743 | | 1971 | 45.538630115307 | | 1970 | 45.566637285124 | | 1969 | 45.592157291881 | | 1968 | 45.532718140505 | | 1967 | 45.46933552773 | | 1966 | 45.40363694274 | | 1965 | 45.328367766462 | | 1964 | 45.245020235579 | | 1963 | 45.147698712184 | | 1962 | 45.038790142148 | | 1961 | 44.924467612272 | | 1960 | 44.801078581012 |
|