2017 13.1643835616438
2016 12.4918032786885
2015 9.83013698630137
2014 9.97260273972603
2013 13.2123287671233
2012 8.64890710382514
2011 11.8109589041096
2010 10.8068493150685
2009 8.78082191780822
2008 9.64207650273224
2007 8.73534246575342
2006 8.77260273972603
2005 11.8972602739726
2004 12.9959016393443
2003 9.76301369863014
2002 8.94657534246575
2001 9.29671232876712