Year Percent 1999-01-01 6.500 2000-01-01 5.800 2001-01-01 5.800 2002-01-01 7.100 2003-01-01 8.300 2004-01-01 8.000 2005-01-01 8.500 2006-01-01 7.900 2007-01-01 6.900 2008-01-01 6.700 2009-01-01 8.000 2010-01-01 7.775 2011-01-01 7.500 2012-01-01 8.600 2013-01-01 8.700 2014-01-01 8.625 2015-01-01 9.200 2016-01-01 8.725 2017-01-01 8.125