| Year | Value | | 2017 | 0.61011571861463 | | 2016 | 0.51766800915237 | | 2015 | 0.43792423910664 | | 2014 | 11.868939927791 | | 2013 | 11.534723090599 | | 2012 | 13.699111741704 | | 2011 | 13.82509968615 | | 2010 | 13.619218984041 | | 2009 | 12.943365680746 | | 2008 | 14.911951236339 | | 2007 | 15.998832727478 | | 2006 | 15.71432046894 | | 2005 | 15.525228551126 | | 2004 | 14.657994640997 | | 2003 | 16.190538060514 | | 2002 | 13.090634306797 | | 2001 | 13.521205196095 | | 2000 | 15.257625385439 |
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