Year Percent 2002 42.68257 2003 44.17366 2004 45.66475 2005 47.15583 2006 48.64692 2007 50.138 2008 51.62909 2009 53.78839 2010 55.98521 2011 58.21954 2012 60.49138 2013 62.80074 2014 65.14761 2015 67.53199 2016 69.95389 2017 72.4133 2018 74.91022 2019 76.58888 2020 78.26753 2021 79.94619 2022 81.62484