Year | Value | 2022 | 50.476891944444 | 2021 | 50.498238228433 | 2020 | 50.51895457263 | 2019 | 50.542637944207 | 2018 | 50.562189998989 | 2017 | 50.558516961453 | 2016 | 50.543248957063 | 2015 | 50.544513774377 | 2014 | 50.544764584577 | 2013 | 50.554414984075 | 2012 | 50.592443899064 | 2011 | 50.636968481068 | 2010 | 50.693983860486 | 2009 | 50.756926880225 | 2008 | 50.818992716136 | 2007 | 50.888347260331 | 2006 | 50.964472707387 | 2005 | 51.046843560991 | 2004 | 51.132987058566 | 2003 | 51.222854864454 | 2002 | 51.312125155173 | 2001 | 51.400601554697 | 2000 | 51.492516076697 | 1999 | 51.582926577034 | 1998 | 51.576787597931 | 1997 | 51.527084253973 | 1996 | 51.522237600218 | 1995 | 51.506759093949 | 1994 | 51.53633297251 | 1993 | 51.516050067634 | 1992 | 51.392857207701 | 1991 | 51.317363116463 | 1990 | 51.291135819376 | 1989 | 51.263282869724 | 1988 | 51.245296091553 | 1987 | 51.173104630769 | 1986 | 51.105480938828 | 1985 | 51.106751151217 | 1984 | 51.104607195377 | 1983 | 51.112916017866 | 1982 | 51.148160299316 | 1981 | 51.202366352373 | 1980 | 51.262090852793 | 1979 | 51.326698253906 | 1978 | 51.395213757263 | 1977 | 51.46868376773 | 1976 | 51.54971032777 | 1975 | 51.63316147067 | 1974 | 51.71762350094 | 1973 | 51.799918982968 | 1972 | 51.832055450448 | 1971 | 51.813055079946 | 1970 | 51.723576700644 | 1969 | 51.558015828501 | 1968 | 51.387777939587 | 1967 | 51.211484200441 | 1966 | 51.015585634657 | 1965 | 50.848129959645 | 1964 | 50.754249116376 | 1963 | 50.647577693185 | 1962 | 50.521911458525 | 1961 | 50.422438065307 | 1960 | 50.31213416404 |
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