Year Number 1996 11.18495 1997 11.205 1998 11.25041 1999 11.27157 2000 11.31734 2001 11.41741 2002 11.50202 2003 11.57095 2004 11.42852 2005 11.30978 2006 11.06086 2007 10.88874 2008 10.75603 2009 10.68708 2010 10.76379 2011 10.68817 2012 10.53622 2013 10.97792 2014 10.82036 2015 10.61154 2016 10.39485 2017 10.35177 2018 10.3459