Year Number 1995 10.70641 1996 9.91409 1997 10.63751 1999 14.54841 2000 14.38273 2001 14.14763 2002 14.68525 2003 15.78745 2004 15.96554 2005 16.69655 2006 17.54547 2007 17.32194 2008 19.04775 2009 17.55612 2010 16.82844 2011 16.26583 2012 16.53644 2013 16.67084 2014 16.57524 2015 16.50996 2016 15.7664 2017 14.94813 2018 13.84031