| Year | Value | | 2020 | 23.565459610028 | | 2017 | 29.052381623166 | | 2016 | 29.763097767267 | | 2015 | 28.224328531736 | | 2014 | 26.477710627724 | | 2013 | 25.670848528627 | | 2012 | 25.425545132767 | | 2011 | 25.578502309036 | | 2010 | 45.664029155827 | | 2009 | 42.665367615799 | | 2008 | 46.528339719586 | | 2007 | 10.90601831075 | | 2006 | 9.6689808757134 | | 2005 | 10.624920772475 | | 2004 | 10.143383098601 | | 2003 | 10.700198505157 | | 2002 | 9.3727435003647 | | 2001 | 23.124357656732 | | 2000 | 26.382978723404 | | 1994 | 51.242798353909 | | 1993 | 51.048692599095 | | 1992 | 52.701421800948 | | 1991 | 55.613126079447 | | 1990 | 58.620689655172 |
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