Year Percent 2000-01-01 46.525 2001-01-01 48.050 2002-01-01 49.275 2003-01-01 50.225 2004-01-01 50.800 2005-01-01 53.075 2006-01-01 54.425 2007-01-01 55.250 2008-01-01 55.725 2009-01-01 54.825 2010-01-01 55.100 2011-01-01 55.475 2012-01-01 55.150 2013-01-01 57.550 2014-01-01 58.550 2015-01-01 60.275 2016-01-01 61.100 2017-01-01 62.200