Year | Value | 2022 | 49.082233424404 | 2021 | 49.000306713185 | 2020 | 48.932448963988 | 2019 | 48.881094887728 | 2018 | 48.845470692718 | 2017 | 48.814294782518 | 2016 | 48.794390494795 | 2015 | 48.781953757443 | 2014 | 48.768145764741 | 2013 | 48.764076314565 | 2012 | 48.768076385741 | 2011 | 48.780622429924 | 2010 | 48.798807040656 | 2009 | 48.816460305899 | 2008 | 48.83335146307 | 2007 | 48.854941167978 | 2006 | 48.878638032075 | 2005 | 48.907116017957 | 2004 | 48.943236714976 | 2003 | 48.975315627542 | 2002 | 48.996914940502 | 2001 | 49.014000228791 | 2000 | 49.036577543866 | 1999 | 49.05916926181 | 1998 | 49.091227609162 | 1997 | 49.133676362491 | 1996 | 49.175780908216 | 1995 | 49.216108746299 | 1994 | 49.25840763884 | 1993 | 49.301625579778 | 1992 | 49.338467788946 | 1991 | 49.408583082107 | 1990 | 49.435934819135 | 1989 | 49.393696581197 | 1988 | 49.363824547628 | 1987 | 49.337031403776 | 1986 | 49.313211476999 | 1985 | 49.287685066633 | 1984 | 49.25812796273 | 1983 | 49.220487947194 | 1982 | 49.180538477068 | 1981 | 49.142719819578 | 1980 | 49.199851135095 | 1979 | 49.358170692914 | 1978 | 49.514288941602 | 1977 | 49.657342723628 | 1976 | 49.798966659982 | 1975 | 49.94272182058 | 1974 | 50.086934561102 | 1973 | 50.22958282642 | 1972 | 50.377319199151 | 1971 | 50.532101625894 | 1970 | 50.688103677673 | 1969 | 50.850441694294 | 1968 | 51.018191691556 | 1967 | 51.193024093577 | 1966 | 51.373215572792 | 1965 | 51.553636810755 | 1964 | 51.746193908032 | 1963 | 51.943861549223 | 1962 | 52.145487078903 | 1961 | 52.354493031074 | 1960 | 52.576033087318 |
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