Year Percent 2002 10.86616 2003 11.09102 2004 12.69901 2005 11.75282 2006 12.12248 2007 12.6857 2008 11.86433 2009 12.51525 2010 12.72043 2011 13.74683 2012 15.6261 2013 16.81711 2014 15.3717 2015 15.07493 2016 15.83589