Year	Percent
1991-01-01	63.2000007629395
1992-01-01	63.3269996643066
1993-01-01	63.2039985656738
1994-01-01	63.0419998168945
1995-01-01	62.8709983825684
1996-01-01	61.4560012817383
1997-01-01	62.3829994201660
1998-01-01	61.3870010375977
1999-01-01	60.8849983215332
2000-01-01	59.7799987792969
2001-01-01	58.7490005493164
2002-01-01	52.6059989929199
2003-01-01	51.6389999389648
2004-01-01	50.8269996643066
2005-01-01	49.6479988098145
2006-01-01	50.5019989013672
2007-01-01	50.7589988708496
2008-01-01	50.8139991760254
2009-01-01	50.0699996948242
2010-01-01	51.1399993896484
2011-01-01	50.2410011291504
2012-01-01	50.8740005493164
2013-01-01	50.5499992370605
2014-01-01	50.9609985351563
2015-01-01	50.6189994812012
2016-01-01	50.4150009155273
2017-01-01	50.5999984741211