Year Percent 2000-01-01 43.750 2001-01-01 42.750 2002-01-01 41.500 2003-01-01 41.225 2004-01-01 41.400 2005-01-01 41.950 2006-01-01 43.175 2007-01-01 45.350 2008-01-01 47.025 2009-01-01 47.525 2010-01-01 47.275 2011-01-01 47.325 2012-01-01 47.575 2013-01-01 47.525 2014-01-01 48.775 2015-01-01 49.775 2016-01-01 50.650 2017-01-01 51.425