Year Percent 1999-01-01 38.050 2000-01-01 38.000 2001-01-01 37.475 2002-01-01 36.250 2003-01-01 35.700 2004-01-01 36.500 2005-01-01 35.100 2006-01-01 34.025 2007-01-01 32.925 2008-01-01 32.175 2009-01-01 31.275 2010-01-01 31.100 2011-01-01 30.750 2012-01-01 29.975 2013-01-01 29.350 2014-01-01 29.200 2015-01-01 29.100 2016-01-01 28.325 2017-01-01 28.175