Year Percent 2000-01-01 30.51 2001-01-01 27.26 2002-01-01 27.40 2003-01-01 25.70 2004-01-01 23.98 2005-01-01 28.54 2006-01-01 37.00 2007-01-01 36.71 2008-01-01 24.39 2009-01-01 31.06 2010-01-01 44.90 2011-01-01 39.03 2012-01-01 49.02 2013-01-01 61.81 2014-01-01 61.53 2015-01-01 67.31 2016-01-01 71.12