Year % of adults 2004 0.2 2005 1.9 2006 2.4 2007 2.1 2008 1.9 2009 1.9 2010 1.8 2011 1.8 2012 1.7 2013 2 2014 2 2015 0.3 2016 0.3 2017 0.4 2018 0.5 2019 0