| Year | Value | | 2021 | 71.14756097561 | | 2020 | 71.636829268293 | | 2019 | 72.043658536585 | | 2018 | 71.886585365854 | | 2017 | 71.641219512195 | | 2016 | 71.82512195122 | | 2015 | 71.977317073171 | | 2014 | 71.985609756098 | | 2013 | 71.573414634146 | | 2012 | 70.55 | | 2011 | 69.824878048781 | | 2010 | 70.291951219512 | | 2009 | 70.528048780488 | | 2008 | 70.015121951219 | | 2007 | 69.322926829268 | | 2006 | 68.616585365854 | | 2005 | 68.42243902439 | | 2004 | 68.643902439024 | | 2003 | 68.02243902439 | | 2002 | 67.152926829268 | | 2001 | 66.734878048781 | | 2000 | 66.100731707317 | | 1999 | 66.488780487805 | | 1998 | 66.157073170732 | | 1997 | 65.798048780488 | | 1996 | 65.767317073171 | | 1995 | 65.644146341463 | | 1994 | 65.900975609756 | | 1993 | 65.585365853659 | | 1992 | 65.196097560976 | | 1991 | 65.031707317073 | | 1990 | 65.068292682927 | | 1989 | 64.66756097561 | | 1988 | 64.58243902439 | | 1987 | 64.654146341463 | | 1986 | 64.248780487805 | | 1985 | 63.833658536585 | | 1984 | 63.466585365854 | | 1983 | 63.3 | | 1982 | 63.192682926829 | | 1981 | 63.07487804878 | | 1980 | 63.449756097561 | | 1979 | 63.954878048781 | | 1978 | 63.414634146341 |
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