Year | Value | 2022 | 50.722659745924 | 2021 | 50.72377940089 | 2020 | 50.721431348595 | 2019 | 50.716894947758 | 2018 | 50.710446861588 | 2017 | 50.703080082816 | 2016 | 50.696827697386 | 2015 | 50.690814504124 | 2014 | 50.682329674137 | 2013 | 50.670086133751 | 2012 | 50.655763791029 | 2011 | 50.640237707191 | 2010 | 50.623956940673 | 2009 | 50.606110582329 | 2008 | 50.587508714719 | 2007 | 50.568628152489 | 2006 | 50.548221921247 | 2005 | 50.525386783798 | 2004 | 50.500045448136 | 2003 | 50.469327847364 | 2002 | 50.435181840959 | 2001 | 50.401406981548 | 2000 | 50.367174826083 | 1999 | 50.333113148422 | 1998 | 50.299127031798 | 1997 | 50.263073863365 | 1996 | 50.224370850775 | 1995 | 50.184594980313 | 1994 | 50.146323879813 | 1993 | 50.10844028518 | 1992 | 50.066886373097 | 1991 | 50.020753615669 | 1990 | 49.968974922849 | 1989 | 49.911860104792 | 1988 | 49.850639943945 | 1987 | 49.78650814218 | 1986 | 49.71821039031 | 1985 | 49.645529297745 | 1984 | 49.569857334164 | 1983 | 49.492803334493 | 1982 | 49.415068600621 | 1981 | 49.33563840131 | 1980 | 49.25617716777 | 1979 | 49.18041986915 | 1978 | 49.10713655681 | 1977 | 49.035423121464 | 1976 | 48.965411945871 | 1975 | 48.89775197926 | 1974 | 48.826910935059 | 1973 | 48.746368627631 | 1972 | 48.657110645314 | 1971 | 48.560870931994 | 1970 | 48.462195066587 | 1969 | 48.36161975156 | 1968 | 48.257813458447 | 1967 | 48.148293906107 | 1966 | 48.033469614507 | 1965 | 47.913864578081 | 1964 | 47.788777670759 | 1963 | 47.658812613189 | 1962 | 47.5226808024 | 1961 | 47.381090511391 | 1960 | 47.233755290669 |
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