Year Percent 2002-01-01 7.89 2003-01-01 9.02 2004-01-01 9.42 2005-01-01 9.88 2006-01-01 9.96 2007-01-01 10.52 2008-01-01 10.64 2009-01-01 12.45 2010-01-01 13.30 2011-01-01 20.20 2012-01-01 18.69 2013-01-01 18.42 2014-01-01 20.69 2015-01-01 22.13