Year % of adults 2004 0.1 2005 0.1 2006 0.2 2007 0.2 2008 0.3 2009 0.4 2010 0.7 2011 1.4 2012 2 2013 2.1 2014 2.4 2015 5.4 2016 7.4 2017 8.2 2018 9.2 2019 10.4