Year Percent 1996-01-01 100.0000 1997-01-01 93.0440 1998-01-01 83.9418 1999-01-01 77.1982 2000-01-01 79.5566 2001-01-01 81.6841 2002-01-01 74.7289 2003-01-01 76.6808 2004-01-01 77.1893 2005-01-01 82.1575 2006-01-01 86.1502 2007-01-01 85.4529 2008-01-01 80.9575 2009-01-01 75.3277 2010-01-01 72.9317 2011-01-01 65.8850 2012-01-01 60.5025 2013-01-01 58.1378 2014-01-01 57.8716 2015-01-01 59.1179 2016-01-01 56.7906