Year Percent 2000 11.92011 2001 11.96847 2002 12.29426 2003 12.62368 2004 13.08153 2005 13.55111 2006 14.03254 2007 14.52604 2008 15.03204 2009 15.55069 2010 16.08231 2011 16.62675 2012 17.18433 2013 17.75521 2014 18.33936 2015 18.93693 2016 19.54805 2017 20.17288 2018 20.26857 2019 20.36426 2020 20.45975 2021 20.55481