Year Percent 2000-01-01 49.400 2001-01-01 50.375 2002-01-01 50.900 2003-01-01 51.250 2004-01-01 52.000 2005-01-01 53.725 2006-01-01 54.775 2007-01-01 58.300 2008-01-01 57.650 2009-01-01 54.650 2010-01-01 52.725 2011-01-01 51.900 2012-01-01 51.600 2013-01-01 52.350 2014-01-01 53.000 2015-01-01 54.125 2016-01-01 55.700 2017-01-01 56.575