Year % of adults 2004 0.4 2005 0.4 2006 0.4 2007 0.4 2008 0.4 2009 0.4 2010 0.4 2011 0.4 2012 0.4 2013 0.4 2014 0.6 2015 0.6 2016 0.6 2017 0.7 2018 0.8 2019 0