Year | Value | 2022 | 49.574709390118 | 2021 | 49.562769270145 | 2020 | 49.545799684356 | 2019 | 49.51905901651 | 2018 | 49.481919157877 | 2017 | 49.443718318069 | 2016 | 49.405162473645 | 2015 | 49.363459961356 | 2014 | 49.320544395978 | 2013 | 49.278436228626 | 2012 | 49.233975533115 | 2011 | 49.186433628212 | 2010 | 49.138111958759 | 2009 | 49.088658079941 | 2008 | 49.036955708757 | 2007 | 49.005964750561 | 2006 | 48.996062813134 | 2005 | 48.983892687875 | 2004 | 48.97038403832 | 2003 | 48.958200613273 | 2002 | 48.945675935234 | 2001 | 48.931567929937 | 2000 | 48.917851205892 | 1999 | 48.910279957395 | 1998 | 48.90483800286 | 1997 | 48.898155652506 | 1996 | 48.890964971582 | 1995 | 48.88475689111 | 1994 | 48.883388753524 | 1993 | 48.886227337407 | 1992 | 48.88982394851 | 1991 | 48.889127139184 | 1990 | 48.879179256442 | 1989 | 48.859485139006 | 1988 | 48.836355418345 | 1987 | 48.8090501194 | 1986 | 48.787510983455 | 1985 | 48.77931273812 | 1984 | 48.773746342181 | 1983 | 48.767969324124 | 1982 | 48.763567435263 | 1981 | 48.749290973658 | 1980 | 48.720009183791 | 1979 | 48.747128594662 | 1978 | 48.795666282467 | 1977 | 48.78177448519 | 1976 | 48.740511150219 | 1975 | 48.697102962456 | 1974 | 48.65967461573 | 1973 | 48.611658737043 | 1972 | 48.552099165793 | 1971 | 48.494803894261 | 1970 | 48.453359458551 | 1969 | 48.42602599274 | 1968 | 48.397621931821 | 1967 | 48.367855085741 | 1966 | 48.336246490266 | 1965 | 48.304994894592 | 1964 | 48.271324814839 | 1963 | 48.23856378702 | 1962 | 48.207669188905 | 1961 | 48.173229528589 | 1960 | 48.139280890786 |
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