Year | Value | 2022 | 50.390940481978 | 2021 | 50.388145808901 | 2020 | 50.388360487102 | 2019 | 50.392665122773 | 2018 | 50.398028508272 | 2017 | 50.405897265048 | 2016 | 50.413925403351 | 2015 | 50.421010722721 | 2014 | 50.428669006939 | 2013 | 50.437235785707 | 2012 | 50.447069750121 | 2011 | 50.457484297153 | 2010 | 50.467581898623 | 2009 | 50.476847508501 | 2008 | 50.487370835572 | 2007 | 50.500784366451 | 2006 | 50.514305612913 | 2005 | 50.527213435513 | 2004 | 50.540157294984 | 2003 | 50.549931370996 | 2002 | 50.554982590613 | 2001 | 50.559369785935 | 2000 | 50.563735628102 | 1999 | 50.54900945086 | 1998 | 50.515167884345 | 1997 | 50.492898630272 | 1996 | 50.479557323402 | 1995 | 50.470841574779 | 1994 | 50.483083379414 | 1993 | 50.50199030622 | 1992 | 50.516269542069 | 1991 | 50.536789915755 | 1990 | 50.561890294199 | 1989 | 50.59015719081 | 1988 | 50.621302746437 | 1987 | 50.658113910572 | 1986 | 50.699565253188 | 1985 | 50.741954940269 | 1984 | 50.786938302104 | 1983 | 50.832942742114 | 1982 | 50.87864054636 | 1981 | 50.925214901728 | 1980 | 50.974495712743 | 1979 | 51.026990946139 | 1978 | 51.083655230387 | 1977 | 51.137791559396 | 1976 | 51.188470977995 | 1975 | 51.241326672368 | 1974 | 51.294699425327 | 1973 | 51.349479585023 | 1972 | 51.407270926818 | 1971 | 51.467429654643 | 1970 | 51.529434217891 | 1969 | 51.594201803257 | 1968 | 51.663248925671 | 1967 | 51.734948453357 | 1966 | 51.809690900625 | 1965 | 51.87639771734 | 1964 | 51.929997044063 | 1963 | 51.98975420443 | 1962 | 52.059376290712 | 1961 | 52.129974802983 | 1960 | 52.208010469374 |
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