Year Percent 1998-01-01 77.0844 1999-01-01 70.7442 2000-01-01 76.8000 2001-01-01 76.5500 2002-01-01 76.0013 2003-01-01 78.4421 2004-01-01 78.4434 2005-01-01 69.8747 2006-01-01 62.5394 2007-01-01 57.0432 2008-01-01 58.4978 2009-01-01 66.2643 2010-01-01 66.1507 2011-01-01 70.3203 2012-01-01 70.7502 2013-01-01 81.8038 2014-01-01 83.5941 2015-01-01 83.7523 2016-01-01 84.3708