Year % of adults 2004 3.1 2005 3.5 2006 4.3 2007 4.7 2008 6.8 2009 8.3 2010 8.7 2011 16.6 2012 18.6 2013 19.2 2014 20.3 2015 23.9 2016 22 2017 22.9 2018 23.6 2019 21.3