| Year | Value | | 2022 | 78.865802748662 | | 2021 | 79.212097687654 | | 2020 | 79.149235430005 | | 2019 | 78.987454935972 | | 2018 | 78.888152011462 | | 2017 | 78.66036308622 | | 2016 | 78.450864583059 | | 2015 | 78.298912545866 | | 2014 | 78.063441301467 | | 2013 | 77.294977480703 | | 2012 | 77.353576843693 | | 2011 | 76.961582158575 | | 2010 | 76.984590578781 | | 2009 | 77.292583600414 | | 2008 | 77.781900116782 | | 2007 | 77.551515828269 | | 2006 | 77.065321460374 | | 2005 | 76.753654032762 | | 2004 | 76.629005491629 | | 2003 | 76.094250470215 | | 2002 | 76.02562796955 | | 2001 | 75.245158498174 | | 2000 | 75.628404291329 | | 1999 | 75.672639886384 | | 1998 | 75.355282582888 | | 1997 | 75.448665798925 | | 1996 | 76.426578185521 | | 1995 | 76.732019003584 | | 1994 | 77.429051855519 | | 1993 | 78.352335374501 | | 1992 | 78.842893952567 | | 1991 | 79.040688480494 |
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