Year Number 1994 14.07831 1995 14.88808 1997 25.97102 2000 15.55606 2002 20.95248 2003 21.68103 2004 18.94906 2005 16.22323 2006 15.8077 2007 16.16082 2008 15.23849 2009 16.92375 2010 17.59193 2011 17.82806 2012 16.18232 2013 19.59875 2014 19.45219 2015 19.07336 2017 17.56537