Year % of adults 2004 2.5625 2005 2.476470588235294 2006 3.8588235294117643 2007 3.810526315789473 2008 5.163157894736844 2009 5.542105263157895 2010 5.589473684210526 2011 7.844999999999999 2012 8.31904761904762 2013 8.442857142857143 2014 8.847619047619046 2015 10.295238095238098 2016 12.852380952380955 2017 13.295238095238094 2018 14.004761904761907 2019 15.01904761904762