| Year | Value | | 2021 | 83.49756097561 | | 2020 | 83.19756097561 | | 2019 | 82.946341463415 | | 2018 | 82.595121951219 | | 2017 | 82.343902439024 | | 2016 | 82.043902439024 | | 2015 | 81.792682926829 | | 2014 | 81.592682926829 | | 2013 | 81.441463414634 | | 2012 | 81.190243902439 | | 2011 | 80.939024390244 | | 2010 | 80.636585365854 | | 2009 | 80.385365853658 | | 2008 | 80.085365853659 | | 2007 | 79.987804878049 | | 2006 | 79.639024390244 | | 2005 | 79.290243902439 | | 2004 | 79.092682926829 | | 2003 | 78.943902439024 | | 2002 | 78.843902439024 | | 2001 | 78.641463414634 | | 2000 | 78.436585365854 | | 1999 | 78.231707317073 | | 1998 | 78.026829268293 | | 1997 | 77.821951219512 | | 1996 | 77.568292682927 | | 1995 | 77.365853658537 | | 1994 | 77.165853658537 | | 1993 | 76.914634146341 | | 1992 | 76.614634146342 | | 1991 | 76.363414634146 | | 1990 | 76.114634146342 | | 1989 | 75.914634146341 | | 1988 | 75.714634146341 | | 1987 | 75.465853658537 | | 1986 | 75.265853658537 | | 1978 | 75.985365853658 | | 1973 | 74.49756097561 |
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