| Year | Value | | 2022 | 58.012713474087 | | 2021 | 57.377713513616 | | 2020 | 60.701048361669 | | 2019 | 64.376843094222 | | 2018 | 63.770362733286 | | 2017 | 64.978445359624 | | 2016 | 66.819016743269 | | 2015 | 68.990414202937 | | 2014 | 60.169055385085 | | 2013 | 59.820590428773 | | 2012 | 61.133499485143 | | 2011 | 55.473779487735 | | 2010 | 53.72654862275 | | 2009 | 55.677903582178 | | 2008 | 51.713109878391 | | 2007 | 50.90233767757 | | 2006 | 53.902520615833 | | 2005 | 53.279606592233 | | 2004 | 53.914430274625 | | 2003 | 55.861819059646 | | 2002 | 58.311673145065 | | 2001 | 63.092348070004 | | 2000 | 62.659280974326 | | 1999 | 63.888879701577 | | 1998 | 70.973579964417 | | 1997 | 63.992948257946 | | 1996 | 59.753134825399 | | 1995 | 64.284206948977 | | 1994 | 65.726736594955 | | 1993 | 66.659059493993 | | 1992 | 70.973519495361 | | 1991 | 72.682477633041 | | 1990 | 78.721909902403 | | 1989 | 83.522002888922 | | 1988 | 90.109107796866 | | 1987 | 83.273487286949 | | 1986 | 86.963611140577 | | 1985 | 82.919736589529 | | 1984 | 80.730617688248 | | 1983 | 78.793494968593 | | 1982 | 80.361380611185 | | 1981 | 85.538711179375 | | 1980 | 78.704426700264 | | 1979 | 72.17793704062 | | 1978 | 73.550701435615 | | 1977 | 62.477614788866 | | 1976 | 59.302591385964 | | 1975 | 69.379476834545 | | 1974 | 57.825212948697 | | 1973 | 61.744009037063 | | 1972 | 70.059989113118 | | 1971 | 74.537669940712 | | 1970 | 75.118139089085 | | 1969 | 74.6681456978 | | 1968 | 72.482095927154 | | 1967 | 78.546567635962 | | 1966 | 78.375588372976 | | 1965 | 78.486188691033 | | 1964 | 82.8521175888 | | 1963 | 87.043921460605 | | 1962 | 88.214069108141 | | 1961 | 90.301113734882 | | 1960 | 92.358957744672 |
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