Year Percent 2002-01-01 1.39 2003-01-01 1.45 2004-01-01 1.51 2005-01-01 1.63 2006-01-01 6.80 2007-01-01 6.84 2008-01-01 7.11 2009-01-01 8.68 2010-01-01 14.23 2011-01-01 16.51 2012-01-01 19.60 2013-01-01 21.69 2014-01-01 24.22 2015-01-01 25.57 2016-01-01 26.87