Year Percent 1999-01-01 62.700 2000-01-01 63.275 2001-01-01 60.000 2002-01-01 61.425 2003-01-01 57.675 2004-01-01 61.100 2005-01-01 60.550 2006-01-01 64.150 2007-01-01 64.000 2008-01-01 65.225 2009-01-01 62.825 2010-01-01 59.500 2011-01-01 58.575 2012-01-01 55.400 2013-01-01 55.050 2014-01-01 54.875 2015-01-01 56.200 2016-01-01 60.000 2017-01-01 57.275