Year % (national estimate) 2008 25.507459459440195 2009 24.881968642833108 2010 23.58848805630524 2011 22.234798782004393 2012 22.14004874051175 2014 21.465021186729356 2015 20.44198153841313 2016 20.674339025606194 2017 19.942455472066264