Year % of adults 2004 0 2005 0.2 2006 0.4 2007 1.6 2008 3.7 2009 5.9 2010 11.9 2011 18.7 2012 24.6 2013 32.1 2014 38.2 2015 35.3 2016 30.6 2017 37 2018 37.9 2019 39.2