Year Percent 2000-01-01 19.81 2001-01-01 22.76 2002-01-01 28.70 2003-01-01 30.15 2004-01-01 30.15 2005-01-01 36.02 2006-01-01 35.00 2007-01-01 37.13 2008-01-01 32.06 2009-01-01 32.49 2010-01-01 32.99 2011-01-01 32.88 2012-01-01 32.43 2013-01-01 32.48 2014-01-01 32.41 2015-01-01 34.09 2016-01-01 33.11