Year Percent 2001-01-01 10.62 2002-01-01 12.23 2003-01-01 14.08 2004-01-01 18.15 2005-01-01 16.69 2006-01-01 17.22 2007-01-01 16.77 2008-01-01 17.10 2009-01-01 18.60 2010-01-01 19.41 2011-01-01 19.47 2012-01-01 21.28 2013-01-01 21.47 2014-01-01 20.88