Year | Value | 2022 | 51.989564283556 | 2021 | 52.066049653411 | 2020 | 52.079657267322 | 2019 | 52.121462625704 | 2018 | 52.190601039774 | 2017 | 52.254518645071 | 2016 | 52.295380670444 | 2015 | 52.332225342601 | 2014 | 52.370762536025 | 2013 | 52.397384078388 | 2012 | 52.421320549515 | 2011 | 52.464980014056 | 2010 | 52.4983565848 | 2009 | 52.507523795336 | 2008 | 52.51636402817 | 2007 | 52.517694149647 | 2006 | 52.514725223457 | 2005 | 52.51797161371 | 2004 | 52.515495329978 | 2003 | 52.496624353557 | 2002 | 52.471211967284 | 2001 | 52.442804079995 | 2000 | 52.411911129669 | 1999 | 52.376167321717 | 1998 | 52.336207688807 | 1997 | 52.296207936443 | 1996 | 52.261306386418 | 1995 | 52.220545630656 | 1994 | 52.171133023426 | 1993 | 52.118601725275 | 1992 | 52.066477918161 | 1991 | 52.02072879464 | 1990 | 51.979758266899 | 1989 | 51.935050037159 | 1988 | 51.892404496148 | 1987 | 51.854756317393 | 1986 | 51.815763753487 | 1985 | 51.774915738336 | 1984 | 51.727678140227 | 1983 | 51.678967217007 | 1982 | 51.638543176824 | 1981 | 51.600890210493 | 1980 | 51.563590233897 | 1979 | 51.544037225345 | 1978 | 51.540301224714 | 1977 | 51.536999351519 | 1976 | 51.538780327056 | 1975 | 51.544352090167 | 1974 | 51.548023718231 | 1973 | 51.548714049305 | 1972 | 51.54884294178 | 1971 | 51.544508245432 | 1970 | 51.537250350594 | 1969 | 51.544816951381 | 1968 | 51.565586766075 | 1967 | 51.587741380131 | 1966 | 51.611948179391 | 1965 | 51.635321012937 | 1964 | 51.656269706256 | 1963 | 51.67741758251 | 1962 | 51.699584527224 | 1961 | 51.725295628389 | 1960 | 51.755893498794 |
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