Year Percent 1999-01-01 31.050 2000-01-01 29.675 2001-01-01 26.925 2002-01-01 25.775 2003-01-01 23.800 2004-01-01 20.825 2005-01-01 19.225 2006-01-01 18.575 2007-01-01 17.700 2008-01-01 17.075 2009-01-01 16.200 2010-01-01 16.550 2011-01-01 16.175 2012-01-01 17.050 2013-01-01 17.025 2014-01-01 20.475 2015-01-01 23.125 2016-01-01 24.625 2017-01-01 24.825