2017 NA
2016 NA
2015 NA
2014 25.6398058252427
2013 25.5509589041096
2012 25.5691428571429
2011 25.8153846153846
2010 26.0048611111111
2009 25.2017699115044
2008 24.9213622291022
2007 25.2722727272727
2006 25.5977653631285
2005 26.1639436619718
2004 25.4946202531646
2003 NA
2002 23.725
2001 NA