Year Percent 2000-01-01 24.78 2001-01-01 26.18 2002-01-01 23.85 2003-01-01 30.01 2004-01-01 31.29 2005-01-01 34.05 2006-01-01 39.00 2007-01-01 42.64 2008-01-01 36.51 2009-01-01 42.57 2010-01-01 42.74 2011-01-01 43.99 2012-01-01 45.79 2013-01-01 45.15 2014-01-01 46.91 2015-01-01 53.51 2016-01-01 54.71