Year | Value | 2022 | 50.397574371191 | 2021 | 50.372266541525 | 2020 | 50.333326293096 | 2019 | 50.286377321526 | 2018 | 50.234759893874 | 2017 | 50.180201408007 | 2016 | 50.124064168759 | 2015 | 50.067989265077 | 2014 | 50.012710941094 | 2013 | 49.958202628021 | 2012 | 49.903102630843 | 2011 | 49.850835309591 | 2010 | 49.801896857178 | 2009 | 49.754322273401 | 2008 | 49.708422257836 | 2007 | 49.663028334384 | 2006 | 49.621773060761 | 2005 | 49.58788025018 | 2004 | 49.556548936876 | 2003 | 49.526541632623 | 2002 | 49.496751740867 | 2001 | 49.466760213957 | 2000 | 49.442337276462 | 1999 | 49.424593586801 | 1998 | 49.414309100854 | 1997 | 49.409931051427 | 1996 | 49.407796533695 | 1995 | 49.407672276153 | 1994 | 49.40848012142 | 1993 | 49.406759214847 | 1992 | 49.402970184272 | 1991 | 49.400448280585 | 1990 | 49.398133406392 | 1989 | 49.396036346697 | 1988 | 49.396118650419 | 1987 | 49.402357953798 | 1986 | 49.414328054513 | 1985 | 49.427747343745 | 1984 | 49.444422544196 | 1983 | 49.466140888441 | 1982 | 49.491728714645 | 1981 | 49.520571627107 | 1980 | 49.553337841803 | 1979 | 49.592461842907 | 1978 | 49.637128184842 | 1977 | 49.683179270492 | 1976 | 49.727882701517 | 1975 | 49.769381577373 | 1974 | 49.808486451005 | 1973 | 49.845438343967 | 1972 | 49.876960465234 | 1971 | 49.903595807635 | 1970 | 49.923402737172 | 1969 | 49.934734425289 | 1968 | 49.93930289794 | 1967 | 49.938650026565 | 1966 | 49.93600359899 | 1965 | 49.931444429889 | 1964 | 49.925303793392 | 1963 | 49.917914887479 | 1962 | 49.911607244711 | 1961 | 49.905139252499 | 1960 | 49.898630636089 |
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