| Year | Value | | 2021 | 73.899371069182 | | 2020 | 73.270440251572 | | 2019 | 73.050314465409 | | 2018 | 72.798742138365 | | 2017 | 69.182389937107 | | 2016 | 68.867924528302 | | 2015 | 69.811320754717 | | 2014 | 67.138364779874 | | 2013 | 66.666666666667 | | 2012 | 65.094339622641 | | 2011 | 64.779874213836 | | 2010 | 64.779874213836 | | 2009 | 64.779874213836 | | 2008 | 64.779874213836 | | 2007 | 64.779874213836 | | 2006 | 63.836477987421 | | 2005 | 63.522012578616 | | 2004 | 62.893081761006 | | 2003 | 61.635220125786 | | 2002 | 61.635220125786 | | 2001 | 61.635220125786 | | 2000 | 61.635220125786 | | 1999 | 61.635220125786 | | 1998 | 61.949685534591 | | 1997 | 61.949685534591 | | 1996 | 62.264150943396 | | 1995 | 62.264150943396 | | 1994 | 61.949685534591 | | 1993 | 61.327044025157 | | 1992 | 60.377358490566 | | 1991 | 59.591194968554 | | 1990 | 59.528301886792 | | 1989 | 59.182389937107 | | 1988 | 58.867924528302 | | 1987 | 57.861635220126 | | 1986 | 57.48427672956 | | 1985 | 57.169811320755 | | 1984 | 56.292452830189 | | 1983 | 55.295597484277 | | 1982 | 55 | | 1981 | 54.622641509434 | | 1980 | 54.261006289308 | | 1979 | 54.166666666667 | | 1978 | 54.119496855346 | | 1977 | 53.710691823899 | | 1976 | 52.955974842767 | | 1975 | 52.562893081761 | | 1974 | 52.279874213837 | | 1973 | 51.698113207547 | | 1972 | 51.289308176101 | | 1971 | 51.25786163522 | | 1970 | 50.943396226415 | | 1969 | 50.943396226415 | | 1968 | 50.786163522013 | | 1967 | 50.786163522013 | | 1966 | 50.566037735849 | | 1965 | 50.566037735849 | | 1964 | 50.251572327044 | | 1963 | 49.937106918239 | | 1962 | 49.937106918239 | | 1961 | 49.308176100629 |
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