Year Percent 2001 53.70295 2002 55.17564 2003 56.72236 2004 53.22186 2005 56.75833 2006 54.68774 2007 53.74489 2008 54.19741 2009 55.28627 2010 57.00038 2011 54.0468 2012 54.01366 2013 54.86464 2014 55.87547 2015 54.35674 2016 51.20034 2017 50.34473