| Year | Value | | 2023 | 61.487933522672 | | 2022 | 61.055761849458 | | 2021 | 60.772122126065 | | 2020 | 60.299101308135 | | 2019 | 61.027100912692 | | 2018 | 60.111786635757 | | 2017 | 59.593501903493 | | 2016 | 59.621841685554 | | 2015 | 59.769214593628 | | 2014 | 58.802488089774 | | 2013 | 57.784318404794 | | 2012 | 56.664920850391 | | 2011 | 55.570082551757 | | 2010 | 54.406875284142 | | 2009 | 53.225816319663 | | 2008 | 52.491367779264 | | 2007 | 51.69566817703 | | 2006 | 51.103673289355 | | 2005 | 50.63994108163 | | 2004 | 50.333109223153 | | 2003 | 49.919171648759 | | 2002 | 49.401069518717 | | 2001 | 49.101341227205 | | 2000 | 48.756539114946 | | 1999 | 48.227222200928 | | 1998 | 47.796559719263 | | 1997 | 47.426126594426 | | 1996 | 47.198082598275 | | 1995 | 46.907186451403 | | 1994 | 46.839750242442 | | 1993 | 46.68886874041 | | 1992 | 46.723153763824 | | 1991 | 46.686733251243 |
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