Year Percent 2003-01-01 45.000 2004-01-01 45.500 2005-01-01 47.100 2006-01-01 49.200 2007-01-01 50.750 2008-01-01 48.700 2009-01-01 50.050 2010-01-01 50.525 2011-01-01 50.025 2012-01-01 52.075 2013-01-01 52.250 2014-01-01 53.725 2015-01-01 55.350 2016-01-01 54.850 2017-01-01 56.375