Year Percent 2004 24.12144 2005 30.48019 2006 23.96081 2007 24.3085 2008 28.69944 2009 26.19097 2010 33.25671 2011 42.95421 2012 45.05981 2013 42.2244 2014 39.71084 2015 37.20917 2016 27.54102