Year % of adults 2004 0 2005 0 2006 0 2007 0 2008 0 2009 0 2010 2.2 2011 3.7 2012 4.9 2013 7 2014 7.7 2015 5.9 2016 7.2 2017 7.1 2018 7.3 2019 7.8