Year Number 1995 12.02628 1998 12.67088 1999 12.98911 2000 13.11259 2001 13.0122 2002 13.13552 2003 13.13813 2004 13.20882 2005 11.89517 2006 11.39496 2007 12.16664 2008 11.23606 2009 12.00535 2010 11.27575 2011 15.51582 2012 17.41974 2013 16.85029 2014 16.57657 2016 14.41713 2017 15.49818 2018 14.95484