Year Percent 1999-01-01 62.450 2000-01-01 63.050 2001-01-01 62.950 2002-01-01 62.950 2003-01-01 63.450 2004-01-01 63.150 2005-01-01 63.150 2006-01-01 63.925 2007-01-01 63.700 2008-01-01 62.725 2009-01-01 60.725 2010-01-01 59.875 2011-01-01 60.725 2012-01-01 61.650 2013-01-01 63.700 2014-01-01 67.825 2015-01-01 70.275 2016-01-01 72.975 2017-01-01 75.225