| Year | Value | | 2021 | 48.08351858 | | 2020 | 43.48954646 | | 2019 | 39.38835219 | | 2018 | 36.04006082 | | 2017 | 31.73579247 | | 2016 | 29.52821808 | | 2015 | 27.1 | | 2014 | 23 | | 2013 | 17.8 | | 2012 | 18.12 | | 2011 | 15.9 | | 2010 | 11.09 | | 2009 | 9.8 | | 2008 | 9.6 | | 2007 | 9.4 | | 2006 | 7.8 | | 2005 | 6.5 | | 2004 | 5.6 | | 2003 | 4.8 | | 2002 | 2.597402597 | | 2001 | 1.415281931 | | 2000 | 1.203855999 | | 1999 | 0.573575476 | | 1998 | 0.301247214 | | 1997 | 0.170996468 | | 1996 | 0.043711246 | | 1995 | 0.036775252 |
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