2017 2.65460526315789
2016 4.3431693989071
2015 2.75561643835616
2014 2.68438356164384
2013 4.09041095890411
2012 3.41311475409836
2011 4.90301369863014
2010 4.43397260273973
2009 3.35890410958904
2008 3.81844262295082
2007 NA
2006 NA
2005 NA
2004 NA
2003 NA
2002 NA
2001 NA