2017 8.47397260273973
2016 7.95983606557377
2015 6.09041095890411
2014 6.36794520547945
2013 8.6745205479452
2012 6.99562841530055
2011 8.31506849315068
2010 8.11452054794521
2009 6.33917808219178
2008 8.39044776119403
2007 5.96190476190476
2006 8.2413698630137
2005 9.1841095890411
2004 8.77431693989071
2003 5.71013698630137
2002 6.36470588235294
2001 6.85521472392638