| Year | Value | | 2021 | 0.91922005571031 | | 2020 | 0.91922005571031 | | 2019 | 0.92178770949721 | | 2018 | 0.92436974789916 | | 2017 | 0.92696629213483 | | 2016 | 0.93088857545839 | | 2015 | 0.93088857545839 | | 2014 | 0.93088857545839 | | 2013 | 0.94766619519095 | | 2012 | 1.0339943342776 | | 2011 | 1.0369318181818 | | 2010 | 1.0541310541311 | | 2009 | 1 | | 2008 | 1 | | 2007 | 1.1510791366907 | | 2006 | 1.0806916426513 | | 2005 | 1.1030478955007 | | 2004 | 1.1611030478955 | | 2003 | 1.1644832605531 | | 2002 | 1.7777777777778 | | 2001 | 1.7910447761194 | | 2000 | 1.7910447761194 | | 1999 | 1.7910447761194 | | 1998 | 1.7910447761194 | | 1997 | 1.7910447761194 | | 1996 | 1.7910447761194 | | 1995 | 1.7910447761194 | | 1994 | 1.7910447761194 | | 1993 | 1.7910447761194 | | 1992 | 1.7910447761194 | | 1991 | 1.7910447761194 | | 1990 | 2.9850746268657 | | 1989 | 2.9850746268657 | | 1988 | 4.4776119402985 | | 1987 | 4.4776119402985 | | 1986 | 5.9701492537313 | | 1985 | 7.4626865671642 | | 1984 | 8.955223880597 | | 1983 | 8.955223880597 | | 1982 | 8.955223880597 | | 1981 | 10.44776119403 | | 1980 | 11.940298507463 | | 1979 | 11.940298507463 | | 1978 | 11.940298507463 | | 1977 | 11.940298507463 | | 1976 | 11.940298507463 | | 1975 | 11.940298507463 | | 1974 | 13.432835820895 | | 1973 | 16.417910447761 | | 1972 | 16.417910447761 | | 1971 | 14.925373134328 | | 1970 | 17.910447761194 | | 1969 | 17.910447761194 | | 1968 | 17.910447761194 | | 1967 | 19.402985074627 | | 1966 | 19.402985074627 | | 1965 | 19.402985074627 | | 1964 | 19.402985074627 | | 1963 | 19.402985074627 | | 1962 | 20.89552238806 | | 1961 | 20.89552238806 |
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