Year Percent 1996-01-01 59.676300000000000 1997-01-01 51.941500000000000 1998-01-01 49.604500000000000 1999-01-01 47.123900000000000 2000-01-01 45.275600000000000 2001-01-01 60.059800000000000 2002-01-01 77.002300000000000 2003-01-01 84.233700000000000 2004-01-01 79.393500000000000 2005-01-01 77.878600000000000 2006-01-01 76.876500000000000 2007-01-01 73.572900000000000 2008-01-01 71.246500000000000 2009-01-01 69.975700000000000 2010-01-01 67.054900000000000 2011-01-01 64.675200000000000 2012-01-01 59.504800000000000 2013-01-01 57.060900000000000 2014-01-01 55.380200000000000 2015-01-01 54.535800000000000 2016-01-01 52.916000000000004