2017 6.91123287671233
2016 6.72349726775956
2015 5.07643835616438
2014 4.83260273972603
2013 7.07945205479452
2012 5.31366120218579
2011 8.70246575342466
2010 8.0186301369863
2009 6.50465753424658
2008 5.08251366120219
2007 6.41086956521739
2006 4.97934131736527
2005 8.74849315068493
2004 8.6551912568306
2003 5.7227397260274
2002 5.05205479452055
2001 4.79342465753425