Year Percent 2002 57.7 2003 51.4 2004 48.8 2005 44.9 2006 48.9 2007 45.3 2008 43.2 2009 41.6 2010 39 2011 37 2012 31.4 2013 28 2014 27.2 2015 26.6 2016 28.9 2017 26.4 2018 24.2 2019 23.5 2020 26.9 2021 26.9 2022 24.7