Year % of adults 2004 5.2 2005 5.01 2006 5.934615384615384 2007 5.792727272727273 2008 6.4750000000000005 2009 7.571428571428572 2010 8.169642857142858 2011 9.874137931034486 2012 10.647457627118644 2013 11.98225806451613 2014 12.249999999999998 2015 13.56935483870968 2016 15.880645161290321 2017 19.008064516129032 2018 21.558730158730157 2019 22.48095238095238