| Year | Value | | 2021 | 62.648221343874 | | 2020 | 62.648221343874 | | 2019 | 62.648221343874 | | 2018 | 62.648221343874 | | 2017 | 62.648221343874 | | 2016 | 63.636363636364 | | 2015 | 63.636363636364 | | 2014 | 63.636363636364 | | 2013 | 63.636363636364 | | 2012 | 63.636363636364 | | 2011 | 63.636363636364 | | 2010 | 63.636363636364 | | 2009 | 61.462450592885 | | 2008 | 55.928853754941 | | 2007 | 49.01185770751 | | 2006 | 49.01185770751 | | 2005 | 47.924901185771 | | 2004 | 47.233201581028 | | 2003 | 46.541501976285 | | 2002 | 48.517786561265 | | 2001 | 47.826086956522 | | 2000 | 50 | | 1999 | 56.02766798419 | | 1998 | 56.02766798419 | | 1997 | 55.0395256917 | | 1996 | 55.0395256917 | | 1995 | 55.0395256917 | | 1994 | 55.0395256917 | | 1993 | 54.051383399209 | | 1992 | 54.150197628458 | | 1991 | 57.509881422925 | | 1990 | 57.509881422925 | | 1989 | 57.114624505929 | | 1988 | 59.090909090909 | | 1987 | 57.806324110672 | | 1986 | 57.312252964427 | | 1985 | 56.620553359684 | | 1984 | 56.620553359684 | | 1983 | 58.00395256917 | | 1982 | 59.881422924901 | | 1981 | 57.806324110672 | | 1980 | 55.632411067194 | | 1979 | 56.324110671937 | | 1978 | 57.411067193676 | | 1977 | 56.719367588933 | | 1976 | 56.02766798419 | | 1975 | 56.126482213439 | | 1974 | 56.719367588933 | | 1973 | 54.051383399209 | | 1972 | 53.557312252964 | | 1971 | 53.063241106719 | | 1970 | 52.766798418972 | | 1969 | 52.667984189723 | | 1968 | 52.470355731225 | | 1967 | 52.470355731225 | | 1966 | 52.272727272727 | | 1965 | 52.173913043478 | | 1964 | 52.075098814229 | | 1963 | 51.97628458498 | | 1962 | 51.877470355731 | | 1961 | 51.778656126482 |
|