2017 22.3364383561644
2016 22.2817910447761
2015 22.2657534246575
2014 22.0676712328767
2013 22.0024657534247
2012 22.1131147540984
2011 22.08
2010 22.6320547945205
2009 21.9723287671233
2008 21.7046448087432
2007 21.878125
2006 22.0775342465753
2005 22.3443213296399
2004 21.8176646706587
2003 22.6021739130435
2002 21.2645161290323
2001 22.1830136986301