Year Percent 2000-01-01 46.9889971447062 2001-01-01 47.7169380891441 2002-01-01 48.4898861736529 2003-01-01 47.4480741005872 2004-01-01 48.4571292701628 2005-01-01 48.5585421805028 2006-01-01 49.0093272815973 2007-01-01 49.1169853761676 2008-01-01 48.8852057271131 2009-01-01 47.8170233458472 2010-01-01 47.9280560496200 2011-01-01 48.2639058394036 2012-01-01 48.6332874858721 2013-01-01 48.9157883184358 2014-01-01 49.7085467543833 2015-01-01 50.0566585666937 2016-01-01 50.2932734338293 2017-01-01 50.7939177041289