Year Percent 1999-01-01 22.250 2000-01-01 21.350 2001-01-01 22.350 2002-01-01 22.825 2003-01-01 24.650 2004-01-01 26.750 2005-01-01 30.275 2006-01-01 33.050 2007-01-01 35.625 2008-01-01 39.225 2009-01-01 39.500 2010-01-01 40.550 2011-01-01 41.350 2012-01-01 43.050 2013-01-01 44.050 2014-01-01 44.775 2015-01-01 46.975 2016-01-01 49.050 2017-01-01 52.950