| Year | Value | | 2025 | 75.102973811578 | | 2024 | 75.08235422787 | | 2023 | 75.090026413779 | | 2022 | 74.23163354978 | | 2021 | 73.958628120336 | | 2020 | 73.482188082461 | | 2019 | 73.03437532925 | | 2018 | 73.161874879153 | | 2017 | 73.100491125404 | | 2016 | 74.35549437726 | | 2015 | 75.579541935505 | | 2014 | 76.91456728538 | | 2013 | 78.368698813034 | | 2012 | 79.492881031838 | | 2011 | 81.467436381467 | | 2010 | 88.175324011422 | | 2009 | 88.342809405559 | | 2008 | 87.831946746972 | | 2007 | 88.090882182919 | | 2006 | 87.397449679983 | | 2005 | 86.115410218093 | | 2004 | 85.804033453727 | | 2003 | 86.10105345066 | | 2002 | 87.147292905136 | | 2001 | 87.195474926551 | | 2000 | 88.408466995925 | | 1999 | 88.93767951964 | | 1998 | 90.405341325792 | | 1997 | 91.578950350311 | | 1996 | 92.604761310514 | | 1995 | 92.30704594393 | | 1994 | 92.28215749189 | | 1993 | 91.977650341119 | | 1992 | 92.472937002221 | | 1991 | 92.842108650956 |
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