| Year | Value | | 2020 | 0.68800451978499 | | 2019 | 0.6968706817076 | | 2018 | 0.69792744628763 | | 2017 | 0.71537952356565 | | 2016 | 0.69556400853111 | | 2015 | 0.71168534949863 | | 2014 | 0.72785306120262 | | 2013 | 0.7442732057993 | | 2012 | 0.76110074779316 | | 2011 | 0.77804333080827 | | 2010 | 0.79606363625264 | | 2009 | 0.81529309786868 | | 2008 | 0.86786943159657 | | 2007 | 0.87826838538623 | | 2006 | 0.89034509775989 | | 2005 | 0.69276508122937 | | 2004 | 0.65193687729842 | | 2003 | 0.40590638896656 | | 2002 | 0.41932237504193 | | 2001 | 0.43353906367605 | | 2000 | 0.4482802847576 | | 1999 | 0.65242921143056 | | 1998 | 0.66540544066801 | | 1997 | 0.67775572487636 | | 1996 | 1.593072372261 | | 1995 | 1.2455971600385 | | 1994 | 0.21116143009782 | | 1993 | 0.21308831018839 | | 1992 | 0.21334061535967 |
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