| Year | Value | | 2022 | 84.024041707705 | | 2021 | 84.049247398196 | | 2020 | 83.113885259702 | | 2019 | 83.199050022718 | | 2018 | 83.055852387672 | | 2017 | 82.956815896514 | | 2016 | 82.840344311363 | | 2015 | 82.661433475593 | | 2014 | 82.006852636145 | | 2013 | 82.4374950602 | | 2012 | 81.584494773341 | | 2011 | 81.948879526957 | | 2010 | 82.274946468927 | | 2009 | 83.233410975062 | | 2008 | 83.877851234226 | | 2007 | 83.825544840297 | | 2006 | 83.859782489054 | | 2005 | 83.980149856894 | | 2004 | 83.175102899788 | | 2003 | 82.862981891212 | | 2002 | 84.004884464434 | | 2001 | 84.905345008037 | | 2000 | 85.017482539746 | | 1999 | 85.516284332983 | | 1998 | 86.566660345859 | | 1997 | 87.825683365834 | | 1996 | 87.889772727502 | | 1995 | 88.129782301815 | | 1994 | 89.527087079807 | | 1993 | 90.705785186482 | | 1992 | 91.026152274845 | | 1991 | 91.539438682824 |
|