2017 6.3786301369863
2016 6.71311475409836
2015 4.21698630136986
2014 4.50794520547945
2013 6.18849315068493
2012 5.79672131147541
2011 7.94082191780822
2010 6.59452054794521
2009 4.61095890410959
2008 5.41857923497268
2007 4.92328767123288
2006 5.03808219178082
2005 7.41150684931507
2004 7.50054644808743
2003 4.38246575342466
2002 4.31890410958904
2001 4.57260273972603