Year Percent 2000-01-01 30.175 2001-01-01 29.400 2002-01-01 28.550 2003-01-01 30.775 2004-01-01 28.500 2005-01-01 30.725 2006-01-01 31.400 2007-01-01 34.100 2008-01-01 35.950 2009-01-01 28.350 2010-01-01 25.350 2011-01-01 31.050 2012-01-01 32.250 2013-01-01 32.350 2014-01-01 33.325 2015-01-01 36.250 2016-01-01 37.475 2017-01-01 40.550