Year Percent 1995-01-01 65.3672592275000 1996-01-01 65.6627315275000 1997-01-01 65.9651779200000 1998-01-01 66.3599285950000 1999-01-01 65.7967306850000 2000-01-01 64.4575099425000 2001-01-01 65.2477356800000 2002-01-01 67.2753233750000 2003-01-01 66.3650359075000 2004-01-01 65.9981463600000 2005-01-01 65.6150157075000 2006-01-01 65.3028262975000 2007-01-01 65.8647438550000 2008-01-01 66.7449699475000 2009-01-01 66.3173355975000 2010-01-01 66.3202135025000 2011-01-01 67.8578747950000 2012-01-01 51.4166666666667 2013-01-01 51.8250000000000 2014-01-01 51.4500000000000 2015-01-01 52.0333333333333 2016-01-01 52.0583333333333 2017-01-01 51.9833333333333