Year Percent 2000-01-01 17.150 2001-01-01 17.375 2002-01-01 17.625 2003-01-01 17.575 2004-01-01 17.900 2005-01-01 17.925 2006-01-01 17.675 2007-01-01 17.800 2008-01-01 17.550 2009-01-01 18.025 2010-01-01 18.475 2011-01-01 18.500 2012-01-01 18.025 2013-01-01 17.900 2014-01-01 17.850 2015-01-01 17.825 2016-01-01 17.550 2017-01-01 17.650