Year Percent 2000-01-01 56.650 2001-01-01 56.625 2002-01-01 56.200 2003-01-01 55.450 2004-01-01 55.600 2005-01-01 54.300 2006-01-01 53.650 2007-01-01 52.625 2008-01-01 52.050 2009-01-01 47.875 2010-01-01 46.825 2011-01-01 45.800 2012-01-01 46.200 2013-01-01 46.250 2014-01-01 48.000 2015-01-01 50.000 2016-01-01 50.850 2017-01-01 50.650