Year % (national estimate) 1999 31.89 2000 29.18 2001 27.88 2002 26.5 2003 30.84 2004 24.98 2005 25.64 2006 23 2007 22.7 2008 24.95 2009 29.147 2010 28.806 2011 29.884 2012 29.825 2013 27.564 2014 28.26 2015 31.433 2016 27.259 2017 38.13 2018 32.397 2019 29.348 2020 29.394