Year | Value | 2022 | 50.388542611532 | 2021 | 50.361117564715 | 2020 | 50.373648525607 | 2019 | 50.427962069505 | 2018 | 50.517826181374 | 2017 | 50.611869132093 | 2016 | 50.712720257955 | 2015 | 50.821827686924 | 2014 | 50.938078721694 | 2013 | 51.06297934668 | 2012 | 51.197901108828 | 2011 | 51.340590625229 | 2010 | 51.490562950033 | 2009 | 51.65588015556 | 2008 | 51.823887252608 | 2007 | 51.898878975063 | 2006 | 51.886781073269 | 2005 | 51.878837861489 | 2004 | 51.875086792198 | 2003 | 51.866882886899 | 2002 | 51.849099122676 | 2001 | 51.827354819876 | 2000 | 51.812622271217 | 1999 | 51.798462248495 | 1998 | 51.778725334723 | 1997 | 51.665028150846 | 1996 | 51.572073168602 | 1995 | 51.596469279227 | 1994 | 51.590847371969 | 1993 | 51.590695274325 | 1992 | 51.641490977285 | 1991 | 51.713700613232 | 1990 | 51.796873810759 | 1989 | 51.874927356553 | 1988 | 51.968445459283 | 1987 | 52.0805515976 | 1986 | 52.183386975279 | 1985 | 52.307944191344 | 1984 | 52.407120594475 | 1983 | 52.458181097017 | 1982 | 52.508121348152 | 1981 | 52.500283994093 | 1980 | 52.49012636911 | 1979 | 52.539583588762 | 1978 | 52.592835876309 | 1977 | 52.641206059801 | 1976 | 52.641985928439 | 1975 | 52.592658011717 | 1974 | 52.525352591059 | 1973 | 52.444514717019 | 1972 | 52.35288078167 | 1971 | 52.25196905782 | 1970 | 52.145461935353 | 1969 | 52.03655364586 | 1968 | 51.928168555069 | 1967 | 51.839673077205 | 1966 | 51.804262637861 | 1965 | 51.803552252412 | 1964 | 51.790474228003 | 1963 | 51.756975809616 | 1962 | 51.70908688066 | 1961 | 51.657784917175 | 1960 | 51.609117122861 |
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