Year % of adults 2004 0 2005 0 2006 0 2007 0 2008 4.7 2009 8.2 2010 10.3 2011 13.7 2012 16.4 2013 19.6 2014 21.8 2015 20.9 2016 21.6 2017 25.3 2018 27.3 2019 31.3