Year Percent 2000-01-01 11.31 2001-01-01 12.51 2002-01-01 13.05 2003-01-01 15.58 2004-01-01 17.17 2005-01-01 17.54 2006-01-01 19.70 2007-01-01 24.45 2008-01-01 16.40 2009-01-01 26.04 2010-01-01 27.61 2011-01-01 27.36 2012-01-01 30.36 2013-01-01 32.94 2014-01-01 31.00 2015-01-01 29.94 2016-01-01 29.14