| Year | Value | | 2021 | 70.233498804927 | | 2020 | 70.233498804927 | | 2019 | 70.233498804927 | | 2018 | 70.233498804927 | | 2017 | 70.233498804927 | | 2016 | 70.233498804927 | | 2015 | 70.233498804927 | | 2014 | 70.233498804927 | | 2013 | 70.233498804927 | | 2012 | 70.785070785071 | | 2011 | 67.383710240853 | | 2010 | 67.383710240853 | | 2009 | 67.199852914139 | | 2008 | 66.83213826071 | | 2007 | 66.096708953852 | | 2006 | 65.637065637066 | | 2005 | 64.717779003493 | | 2004 | 63.982349696635 | | 2003 | 63.614635043206 | | 2002 | 63.246920389778 | | 2001 | 62.879205736349 | | 2000 | 62.51149108292 | | 1999 | 61.959919102776 | | 1998 | 61.592204449347 | | 1997 | 61.224489795918 | | 1996 | 60.48906048906 | | 1995 | 60.121345835632 | | 1994 | 59.753631182203 | | 1993 | 59.385916528774 | | 1992 | 58.926273211987 | | 1991 | 58.558558558559 | | 1990 | 58.098915241772 | | 1989 | 57.731200588343 | | 1988 | 57.731200588343 | | 1987 | 57.1796286082 | | 1986 | 56.811913954771 | | 1985 | 56.811913954771 | | 1984 | 56.719985291414 | | 1983 | 55.800698657842 | | 1982 | 55.800698657842 | | 1981 | 55.800698657842 | | 1980 | 55.800698657842 | | 1979 | 55.708769994484 | | 1978 | 54.789483360912 | | 1977 | 52.950910093767 | | 1976 | 52.950910093767 | | 1975 | 52.950910093767 | | 1974 | 52.950910093767 | | 1973 | 52.950910093767 | | 1972 | 52.950910093767 | | 1971 | 52.950910093767 | | 1970 | 56.536127964699 | | 1969 | 56.536127964699 | | 1968 | 56.536127964699 | | 1967 | 56.536127964699 | | 1966 | 56.536127964699 | | 1965 | 56.536127964699 | | 1964 | 56.444199301342 | | 1963 | 56.444199301342 | | 1962 | 56.444199301342 | | 1961 | 56.444199301342 |
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