2017 25.3693150684932
2016 25.4109289617486
2015 25.3334246575342
2014 25.1956164383562
2013 25.0501369863014
2012 25.2527322404372
2011 25.0906849315068
2010 25.6857534246575
2009 25.278904109589
2008 24.898087431694
2007 25.3578082191781
2006 25.2572602739726
2005 25.1424460431655
2004 24.9822404371585
2003 24.8931034482759
2002 NA
2001 NA