2017 5.40383561643836
2016 5.34426229508197
2015 3.86301369863014
2014 4.11260273972603
2013 5.86712328767123
2012 4.52978142076503
2011 6.59808219178082
2010 5.19671232876712
2009 4.12191780821918
2008 5.27349726775956
2007 4.52739726027397
2006 4.65397260273973
2005 6.04164383561644
2004 6.86284153005465
2003 3.99890410958904
2002 3.91369863013699
2001 3.2786301369863