| Year | Value | | 2021 | 82.364532203935 | | 2020 | 82.268576382362 | | 2019 | 82.358734224734 | | 2018 | 83.017561539383 | | 2017 | 83.694052767579 | | 2016 | 84.363113808062 | | 2015 | 84.067583230834 | | 2014 | 84.133501524594 | | 2013 | 80.876884297777 | | 2012 | 81.229515932752 | | 2011 | 80.731831917767 | | 2010 | 81.090988496899 | | 2009 | 81.518469765753 | | 2008 | 81.946371161717 | | 2007 | 81.343971448658 | | 2006 | 81.000359423843 | | 2005 | 81.782393662795 | | 2004 | 83.564011738017 | | 2003 | 87.499068560706 | | 2002 | 87.844427385225 | | 2001 | 89.080947290165 | | 2000 | 89.93952178439 | | 1999 | 91.220578959823 | | 1998 | 90.504969230088 | | 1997 | 89.738330438897 | | 1996 | 88.988975183071 | | 1995 | 89.611638555547 | | 1994 | 89.578155909694 | | 1993 | 89.47471571384 | | 1992 | 89.623007417733 | | 1991 | 89.709536686409 |
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