Year Percent 2001 59.10933 2002 57.90029 2003 61.23986 2004 58.0768 2005 60.32094 2006 60.27044 2007 59.14694 2008 59.89206 2009 60.76718 2010 61.05614 2011 59.17589 2012 59.02112 2013 60.24567 2014 61.5498 2015 60.22953 2016 57.02983 2017 56.55081