| Year | Value | | 2021 | 50.84164945 | | 2020 | 47.51234167 | | 2019 | 44.40104984 | | 2018 | 41.5 | | 2017 | 37.9 | | 2016 | 34.50932609 | | 2015 | 28.80594156 | | 2014 | 23.4 | | 2013 | 19.7 | | 2012 | 16 | | 2011 | 12.3 | | 2010 | 10.5 | | 2009 | 9.3 | | 2008 | 8.3 | | 2007 | 7.3 | | 2006 | 6.5 | | 2005 | 5.7 | | 2004 | 5.1 | | 2003 | 4.548854908 | | 2002 | 3.39174627 | | 2001 | 1.738201782 | | 2000 | 0.712332905 | | 1999 | 0.592652945 | | 1998 | 0.466590444 | | 1997 | 0.095476021 | | 1996 | 0.019534871 | | 1995 | 0.002998005 |
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