Year | Value | 2022 | 51.361397620042 | 2021 | 51.377951508873 | 2020 | 51.39222609662 | 2019 | 51.406274239974 | 2018 | 51.422403986349 | 2017 | 51.43952293494 | 2016 | 51.457758710633 | 2015 | 51.47768969278 | 2014 | 51.496519655399 | 2013 | 51.516704602717 | 2012 | 51.542690635046 | 2011 | 51.572801542101 | 2010 | 51.607719903669 | 2009 | 51.646640462379 | 2008 | 51.686517143297 | 2007 | 51.698048447838 | 2006 | 51.669960155682 | 2005 | 51.627310505903 | 2004 | 51.578435273156 | 2003 | 51.525215369171 | 2002 | 51.467656916739 | 2001 | 51.405805361908 | 2000 | 51.336613476764 | 1999 | 51.249640512501 | 1998 | 51.209173370941 | 1997 | 51.23858069276 | 1996 | 51.279662884384 | 1995 | 51.322984616748 | 1994 | 51.34187916677 | 1993 | 51.336086447485 | 1992 | 51.331659980505 | 1991 | 51.327995570195 | 1990 | 51.324276062105 | 1989 | 51.321034191672 | 1988 | 51.317697153133 | 1987 | 51.338700502761 | 1986 | 51.370619226559 | 1985 | 51.388064489308 | 1984 | 51.406730778926 | 1983 | 51.423958430884 | 1982 | 51.440175450931 | 1981 | 51.456703800723 | 1980 | 51.474087452007 | 1979 | 51.492368729205 | 1978 | 51.510206049088 | 1977 | 51.527091910633 | 1976 | 51.54509944971 | 1975 | 51.568662166858 | 1974 | 51.600824198672 | 1973 | 51.634519485557 | 1972 | 51.662851743267 | 1971 | 51.687576963951 | 1970 | 51.710358667984 | 1969 | 51.731750656623 | 1968 | 51.753610253825 | 1967 | 51.772910137945 | 1966 | 51.786690923182 | 1965 | 51.798820130704 | 1964 | 51.809096971427 | 1963 | 51.815350619011 | 1962 | 51.81599592541 | 1961 | 51.813673128664 | 1960 | 51.815880395937 |
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