Year Percent 2000-01-01 58.150 2001-01-01 57.325 2002-01-01 55.725 2003-01-01 56.025 2004-01-01 55.900 2005-01-01 56.600 2006-01-01 59.275 2007-01-01 74.475 2008-01-01 70.025 2009-01-01 62.750 2010-01-01 56.000 2011-01-01 53.575 2012-01-01 51.900 2013-01-01 51.625 2014-01-01 50.175 2015-01-01 50.150 2016-01-01 52.675 2017-01-01 47.875