| Year | Value | | 2021 | 86.989661319073 | | 2020 | 87.287700534759 | | 2019 | 87.585739750446 | | 2018 | 87.883778966132 | | 2017 | 88.181818181818 | | 2016 | 88.479857397504 | | 2015 | 88.777896613191 | | 2014 | 89.075864527629 | | 2013 | 89.373832442068 | | 2012 | 89.671800356506 | | 2011 | 89.969768270945 | | 2010 | 90.267736185383 | | 2009 | 90.565668449198 | | 2008 | 90.863600713013 | | 2007 | 91.161532976827 | | 2006 | 91.459465240642 | | 2005 | 91.757397504456 | | 2004 | 92.055329768271 | | 2003 | 92.353262032086 | | 2002 | 92.6511942959 | | 2001 | 92.949126559715 | | 2000 | 93.247058823529 | | 1999 | 93.544991087344 | | 1998 | 93.842923351159 | | 1997 | 94.140855614973 | | 1996 | 94.438787878788 | | 1995 | 94.736720142602 | | 1994 | 95.034652406417 | | 1993 | 95.332584670232 | | 1992 | 95.630516934046 | | 1991 | 95.928449197861 | | 1990 | 96.226381461676 |
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