Year % of adults 2004 9.5 2005 12.5 2006 18.2 2007 19.7 2008 20.6 2009 20.6 2010 22.4 2011 33.1 2012 33.4 2013 33.7 2014 34.2 2015 34.7 2016 35.1 2017 35.2 2018 26.9 2019 22.9