2017 26.8391780821918
2016 26.9808864265928
2015 26.8649315068493
2014 26.5043835616438
2013 26.6087671232877
2012 26.6357923497268
2011 26.5980821917808
2010 27.1139726027397
2009 26.7345205479452
2008 26.5770491803279
2007 26.9681948424069
2006 27.0473537604457
2005 27.1016574585635
2004 26.711797752809
2003 26.9598870056497
2002 26.7100558659218
2001 26.8261111111111