Year Percent 1996-01-01 83.9865 1997-01-01 84.5082 1998-01-01 84.6153 1999-01-01 84.9150 2000-01-01 84.5356 2001-01-01 84.8474 2002-01-01 82.8656 2003-01-01 81.7654 2004-01-01 77.8760 2005-01-01 73.3314 2006-01-01 65.6667 2007-01-01 52.6510 2008-01-01 52.6502 2009-01-01 44.4459 2010-01-01 38.9495 2011-01-01 37.4418 2012-01-01 40.3909 2013-01-01 40.5539 2014-01-01 37.8355 2015-01-01 50.4981 2016-01-01 40.7196