Year Percent 1996-01-01 67.456200000000000 1997-01-01 65.934700000000000 1998-01-01 63.604900000000000 1999-01-01 63.378000000000000 2000-01-01 63.795900000000000 2001-01-01 65.035100000000000 2002-01-01 65.009000000000000 2003-01-01 66.745800000000000 2004-01-01 66.583600000000000 2005-01-01 65.370700000000000 2006-01-01 64.259300000000000 2007-01-01 64.143400000000000 2008-01-01 63.423600000000000 2009-01-01 62.461000000000006 2010-01-01 61.025600000000000 2011-01-01 62.121100000000000 2012-01-01 63.117500000000000 2013-01-01 62.791700000000000 2014-01-01 62.539400000000000 2015-01-01 60.588200000000000 2016-01-01 55.458400000000000