2017 4.32191780821918
2016 4.36010928961749
2015 2.88191780821918
2014 3.09671232876712
2013 5.31616438356164
2012 4.93989071038251
2011 7.27835616438356
2010 5.20657534246575
2009 4.27342465753425
2008 5.0103825136612
2007 3.8772602739726
2006 4.22438356164384
2005 6.02164383561644
2004 6.29617486338798
2003 3.90876712328767
2002 4.0186301369863
2001 4.26794520547945