Year Percent 2000-01-01 52.325 2001-01-01 53.700 2002-01-01 54.525 2003-01-01 54.350 2004-01-01 54.175 2005-01-01 54.550 2006-01-01 55.500 2007-01-01 57.075 2008-01-01 58.125 2009-01-01 58.350 2010-01-01 56.275 2011-01-01 55.575 2012-01-01 55.600 2013-01-01 54.925 2014-01-01 53.900 2015-01-01 54.525 2016-01-01 54.875 2017-01-01 55.700