| Year | Value | | 2022 | 49.984581932219 | | 2021 | 50.14074959552 | | 2020 | 50.013097198583 | | 2019 | 51.096635166674 | | 2018 | 50.81412210864 | | 2017 | 50.102022655348 | | 2016 | 49.977477929753 | | 2015 | 49.428045996222 | | 2014 | 48.762658401757 | | 2013 | 48.048234586541 | | 2012 | 47.48670740165 | | 2011 | 46.489254227997 | | 2010 | 45.659330150724 | | 2009 | 45.192705351622 | | 2008 | 44.919690815681 | | 2007 | 44.34602025393 | | 2006 | 43.744074514651 | | 2005 | 43.08434858888 | | 2004 | 42.361515395034 | | 2003 | 41.520870374812 | | 2002 | 41.162243915141 | | 2001 | 40.788045000834 | | 2000 | 40.270810020478 | | 1999 | 39.99126614094 | | 1998 | 39.736383698491 | | 1997 | 39.66414673866 | | 1996 | 39.438624472608 | | 1995 | 39.129394136125 | | 1994 | 38.938978505777 | | 1993 | 38.78292209605 | | 1992 | 38.626073209843 | | 1991 | 38.500932894922 |
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