Year Percent 1999-01-01 57.150 2000-01-01 55.300 2001-01-01 55.175 2002-01-01 55.525 2003-01-01 56.400 2004-01-01 56.450 2005-01-01 57.800 2006-01-01 59.875 2007-01-01 61.075 2008-01-01 62.575 2009-01-01 60.350 2010-01-01 58.200 2011-01-01 58.775 2012-01-01 59.100 2013-01-01 58.600 2014-01-01 59.450 2015-01-01 60.875 2016-01-01 62.100 2017-01-01 62.375