Year Percent 2001-01-01 58.400 2002-01-01 58.475 2003-01-01 58.400 2004-01-01 58.275 2005-01-01 58.750 2006-01-01 59.250 2007-01-01 59.675 2008-01-01 59.800 2009-01-01 59.375 2010-01-01 58.950 2011-01-01 59.675 2012-01-01 60.075 2013-01-01 60.475 2014-01-01 60.875 2015-01-01 61.325 2016-01-01 61.475 2017-01-01 62.050