Year Percent 2002-01-01 11.95 2003-01-01 13.04 2004-01-01 16.43 2005-01-01 22.40 2006-01-01 21.57 2007-01-01 21.57 2008-01-01 21.57 2009-01-01 26.68 2010-01-01 27.99 2011-01-01 29.88 2012-01-01 36.27 2013-01-01 34.44 2014-01-01 34.74 2015-01-01 36.66 2016-01-01 39.93