2017 22.9794520547945
2016 23.0027322404372
2015 22.9175342465753
2014 23.0550684931507
2013 23.1008219178082
2012 23.2215846994536
2011 23.1347945205479
2010 23.3104109589041
2009 22.8491582491583
2008 22.5312703583062
2007 22.8181415929204
2006 22.8790633608815
2005 22.9837142857143
2004 22.4988764044944
2003 22.7422818791946
2002 22.8970394736842
2001 22.6553797468354