Year % of adults 2004 6.538235294117647 2005 6.600000000000001 2006 7.171428571428573 2007 7.62 2008 8.528571428571428 2009 10.59142857142857 2010 11.162857142857142 2011 12.982857142857146 2012 14.214285714285715 2013 13.847368421052632 2014 15.06578947368421 2015 15.723684210526315 2016 16.210526315789476 2017 21.797368421052635 2018 24.184210526315788 2019 24.855263157894736