Year Percent 2000-01-01 52.0626175571395 2001-01-01 52.8515875213429 2002-01-01 53.5502253767217 2003-01-01 52.9988872833984 2004-01-01 54.2611387444365 2005-01-01 54.5414446063894 2006-01-01 54.9209008739444 2007-01-01 54.9181440355327 2008-01-01 54.8290707393512 2009-01-01 54.0061485058257 2010-01-01 54.5443956710194 2011-01-01 54.8927762858444 2012-01-01 55.2359423610329 2013-01-01 55.6299242803918 2014-01-01 57.0664681081548 2015-01-01 57.8507363129577 2016-01-01 58.2998395810046 2017-01-01 58.9995490206778