2017 23.3112328767123
2016 23.396174863388
2015 23.3312328767123
2014 23.1786301369863
2013 23.0167123287671
2012 23.2931693989071
2011 23.047397260274
2010 23.2
2009 23.0621917808219
2008 22.7786885245902
2007 23.1194029850746
2006 22.8419178082192
2005 23.3939726027397
2004 22.9677595628415
2003 23.1353424657534
2002 23.241095890411
2001 23.1852054794521