Year % of adults 2004 6.4402061855670105 2005 6.407142857142858 2006 7.3728070175438605 2007 9.703508771929824 2008 10.276315789473687 2009 11.839130434782607 2010 12.48 2011 13.93304347826087 2012 14.436440677966104 2013 16.134126984126983 2014 16.827777777777776 2015 18.279527559055122 2016 18.314960629921256 2017 19.456692913385826 2018 21.14488188976378 2019 23.46141732283464