Year % of adults 2004 0.1 2005 0.9 2006 1.2 2007 1 2008 0.9 2009 0.9 2010 0.7 2011 0.9 2012 0.8 2013 1 2014 1 2015 0.3 2016 0.3 2017 0.3 2018 0.3 2019 0