Year % of adults 2004 16.6 2005 16.1 2006 16.1 2007 14.5 2008 31.2 2009 30.4 2010 29.6 2011 29 2012 31 2013 29 2014 32 2015 34.2 2016 31 2017 31 2018 30.7 2019 31.6