| Year | Value | | 2014 | 50.846545950256 | | 2013 | 47.873825824728 | | 2012 | 48.901642922543 | | 2011 | 46.924419629983 | | 2010 | 43.730176879555 | | 2009 | 42.087765149023 | | 2008 | 38.692541495001 | | 2007 | 38.528990010856 | | 2006 | 34.319125261883 | | 2005 | 36.08747922534 | | 2004 | 32.91716806122 | | 2003 | 29.223016574954 | | 2002 | 29.783606444723 | | 2001 | 30.087861542643 | | 2000 | 31.92039003103 |
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