Year Percent 1998-01-01 70.7804 1999-01-01 78.1903 2000-01-01 63.5000 2001-01-01 65.2000 2002-01-01 65.4046 2003-01-01 67.3687 2004-01-01 67.1942 2005-01-01 73.4751 2006-01-01 65.0166 2007-01-01 55.8560 2008-01-01 49.9546 2009-01-01 54.7077 2010-01-01 57.4073 2011-01-01 61.8853 2012-01-01 67.6339 2013-01-01 80.5847 2014-01-01 84.6481 2015-01-01 85.0161 2016-01-01 87.1704