Year Percent 2000 31.98625 2001 33.84087 2002 35.73418 2003 37.66619 2004 39.63689 2005 41.64629 2006 43.69439 2007 45.78118 2008 47.90666 2009 50.07084 2010 52.27372 2011 54.51529 2012 56.79556 2013 59.11453 2014 61.47219 2015 63.86854 2016 66.3036 2017 68.77734 2018 71.28979 2019 73.84093 2020 76.43076 2021 79.05929 2022 79.05929