Year % of adults 2004 0 2005 0 2006 0 2007 0 2008 0 2009 14 2010 9.9 2011 14.6 2012 17.2 2013 19.6 2014 21.1 2015 23.4 2016 24.6 2017 25 2018 29 2019 31.6