Year Number 1995 14.02267 1996 13.70084 1997 13.74006 1998 13.53395 1999 13.01032 2000 12.43584 2001 12.70587 2002 12.79852 2003 13.05152 2004 12.08512 2005 11.33992 2006 11.29174 2007 11.22138 2008 11.03265 2009 10.78595 2010 10.6326 2011 10.33829 2012 10.12762 2013 10.98159 2014 11.02954 2015 10.67695 2016 10.47361 2017 10.42113 2018 10.47686