Year % 1997 9 1998 9 1999 9 2001 9 2002 9 2003 9 2004 10.8695652173913 2005 10.8695652173913 2006 10.8695652173913 2007 10.8695652173913 2008 7.89473684210526 2009 8.26086956521739 2010 8.26086956521739 2011 8.26086956521739 2013 10.9090909090909 2014 10.9090909090909 2015 10.9090909090909 2016 10.9090909090909 2017 12.7272727272727 2018 12.7272727272727 2019 13.0909090909091 2020 13.0909090909091 2021 14.5454545454545 2022 14.5454545454545 2023 14.5454545454545