Year % (national estimate) 2006 17.6352107176395 2007 16.007100511865023 2008 15.771582416805074 2009 14.994270853620872 2010 14.533276764830969 2012 13.561497082938832 2014 11.91817508622138 2015 15.111411558267132 2016 14.25272489883999