Year % of adults 2004 21.73095238095238 2005 23.00232558139535 2006 25.377777777777776 2007 29.279999999999998 2008 31.328260869565216 2009 32.946808510638306 2010 36.03829787234043 2011 43.202127659574465 2012 42.416666666666664 2013 45.52244897959184 2014 45.80612244897959 2015 48.80000000000001 2016 50.37346938775509 2017 49.85510204081632 2018 50.296000000000014 2019 49.647999999999996