Year Percent 2000-01-01 37.26 2001-01-01 35.65 2002-01-01 32.55 2003-01-01 35.55 2004-01-01 35.82 2005-01-01 40.18 2006-01-01 41.11 2007-01-01 40.36 2008-01-01 34.37 2009-01-01 39.86 2010-01-01 42.19 2011-01-01 40.36 2012-01-01 45.74 2013-01-01 48.41 2014-01-01 53.04 2015-01-01 55.70 2016-01-01 59.14