Year Percent 2000-01-01 50.725 2001-01-01 51.100 2002-01-01 51.650 2003-01-01 52.850 2004-01-01 52.900 2005-01-01 54.000 2006-01-01 57.025 2007-01-01 57.750 2008-01-01 57.775 2009-01-01 52.500 2010-01-01 50.375 2011-01-01 53.775 2012-01-01 55.150 2013-01-01 56.050 2014-01-01 56.625 2015-01-01 58.275 2016-01-01 58.625 2017-01-01 59.975