Year Percent 1999-01-01 25.025 2000-01-01 26.550 2001-01-01 29.725 2002-01-01 29.300 2003-01-01 32.275 2004-01-01 30.250 2005-01-01 29.975 2006-01-01 29.475 2007-01-01 27.975 2008-01-01 27.200 2009-01-01 28.225 2010-01-01 32.450 2011-01-01 32.875 2012-01-01 35.900 2013-01-01 38.925 2014-01-01 38.950 2015-01-01 38.275 2016-01-01 35.000 2017-01-01 37.525