Year Percent 2000 20.435 2001 20.62504 2002 20.819 2003 21.01688 2004 21.21868 2005 22.13309 2006 23.05825 2007 23.99434 2008 24.94208 2009 25.90062 2010 26.87067 2011 27.8486 2012 28.83499 2013 29.82933 2014 30.83106 2015 31.84077 2016 32.75394 2017 33.52835 2018 34.22833 2019 34.49241 2020 34.75593 2021 35.01829