2017 12.5172602739726
2016 11.0338797814208
2015 9.11178082191781
2014 8.47561643835616
2013 12.1243835616438
2012 9.46229508196721
2011 11.958904109589
2010 11.8684931506849
2009 9.84
2008 12.8440476190476
2007 NA
2006 NA
2005 NA
2004 NA
2003 NA
2002 NA
2001 NA