Year Percent 2001-01-01 11.750 2002-01-01 12.875 2003-01-01 13.725 2004-01-01 17.075 2005-01-01 21.675 2006-01-01 21.525 2007-01-01 19.325 2008-01-01 20.150 2009-01-01 24.900 2010-01-01 24.775 2011-01-01 22.750 2012-01-01 23.600 2013-01-01 23.525 2014-01-01 22.875 2015-01-01 20.325 2016-01-01 18.825 2017-01-01 17.875