2017 24.1435897435897
2016 24.5743169398907
2015 24.347397260274
2014 24.6956164383562
2013 24.6397260273973
2012 24.7825136612022
2011 24.5846575342466
2010 24.8493150684932
2009 24.5653495440729
2008 NA
2007 23.6582089552239
2006 25.0871921182266
2005 24.456401384083
2004 24.1067055393586
2003 24.2694267515924
2002 24.6566037735849
2001 25.1272189349112