Year Percent 1996-01-01 80.5538 1997-01-01 76.9644 1998-01-01 73.4020 1999-01-01 73.5876 2000-01-01 70.9515 2001-01-01 67.5874 2002-01-01 67.7099 2003-01-01 64.1820 2004-01-01 65.2303 2005-01-01 65.5504 2006-01-01 68.1307 2007-01-01 78.4237 2008-01-01 77.8034 2009-01-01 58.0433 2010-01-01 68.6571 2011-01-01 70.8129 2012-01-01 65.4491 2013-01-01 67.6212 2014-01-01 78.0572