Year % of adults 2004 0.35714285714285715 2005 0.7333333333333333 2006 0.7875 2007 1.23125 2008 3.9187499999999997 2009 9.464705882352941 2010 12.099999999999998 2011 14.770588235294115 2012 15.058823529411764 2013 15.676470588235293 2014 18.935294117647057 2015 23.53529411764706 2016 21.676470588235293 2017 23.223529411764705 2018 22.935294117647057 2019 21.35294117647059