Year Percent 1996-01-01 57.7546 1997-01-01 56.8081 1998-01-01 57.8801 1999-01-01 57.2130 2000-01-01 58.4391 2001-01-01 60.8015 2002-01-01 59.5488 2003-01-01 59.8312 2004-01-01 57.9743 2005-01-01 58.3414 2006-01-01 59.3365 2007-01-01 53.9295 2008-01-01 58.3189 2009-01-01 58.0749 2010-01-01 59.6233 2011-01-01 59.4374 2012-01-01 58.1638 2013-01-01 57.3202 2014-01-01 60.1489 2015-01-01 55.8673 2016-01-01 64.0831