Year Percent 2001 35 2002 37 2003 41 2004 42 2005 40 2006 45 2007 45 2008 44 2009 45 2010 48 2011 50 2012 49 2013 50 2014 52 2015 52 2016 50 2017 53 2018 55 2019 59 2020 55