Year | Value | 2022 | 52.393475656178 | 2021 | 52.381826454701 | 2020 | 52.366770484866 | 2019 | 52.349751608901 | 2018 | 52.324490921623 | 2017 | 52.292068462692 | 2016 | 52.261559456748 | 2015 | 52.238092165931 | 2014 | 52.222520688375 | 2013 | 52.21275334072 | 2012 | 52.206315918633 | 2011 | 52.201561292995 | 2010 | 52.197272700806 | 2009 | 52.193283149363 | 2008 | 52.18856844623 | 2007 | 52.182737270254 | 2006 | 52.146049771677 | 2005 | 52.0796837665 | 2004 | 52.01829793121 | 2003 | 51.963654639431 | 2002 | 51.915974564464 | 2001 | 51.874678006945 | 2000 | 51.83660872014 | 1999 | 51.799994328015 | 1998 | 51.763687954783 | 1997 | 51.725213850319 | 1996 | 51.682295062738 | 1995 | 51.635322044572 | 1994 | 51.58707881451 | 1993 | 51.538531344505 | 1992 | 51.507256755243 | 1991 | 51.491630761005 | 1990 | 51.468993301695 | 1989 | 51.420678925975 | 1988 | 51.37649793828 | 1987 | 51.35058809599 | 1986 | 51.309229039742 | 1985 | 51.254840050468 | 1984 | 51.17816645369 | 1983 | 51.059198068951 | 1982 | 50.916214773178 | 1981 | 50.726670539898 | 1980 | 50.526326061346 | 1979 | 50.387059357222 | 1978 | 50.286942065403 | 1977 | 50.211537155904 | 1976 | 50.156807595113 | 1975 | 50.118022905986 | 1974 | 50.089393980847 | 1973 | 50.064680891751 | 1972 | 50.037716137162 | 1971 | 50.008333310859 | 1970 | 49.976485801679 | 1969 | 49.983602183883 | 1968 | 50.038176130639 | 1967 | 50.101427557472 | 1966 | 50.174624575531 | 1965 | 50.253718659439 | 1964 | 50.334844289651 | 1963 | 50.417080585163 | 1962 | 50.495928785314 | 1961 | 50.540383420733 | 1960 | 50.550510969022 |
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