Year	Percent
1991-01-01	63.4010009765625
1992-01-01	65.1660003662109
1993-01-01	65.0690002441406
1994-01-01	65.1449966430664
1995-01-01	65.2740020751953
1996-01-01	65.1050033569336
1997-01-01	65.0999984741211
1998-01-01	65.7149963378906
1999-01-01	66.2289962768555
2000-01-01	66.6409988403320
2001-01-01	66.8270034790039
2002-01-01	67.0550003051758
2003-01-01	67.2070007324219
2004-01-01	66.9440002441406
2005-01-01	66.6179962158203
2006-01-01	66.2310028076172
2007-01-01	65.7750015258789
2008-01-01	65.1969985961914
2009-01-01	64.4970016479492
2010-01-01	63.6529998779297
2011-01-01	62.6640014648438
2012-01-01	61.5159988403320
2013-01-01	60.8590011596680
2014-01-01	59.1370010375977
2015-01-01	59.0060005187988
2016-01-01	59.0149993896484
2017-01-01	59.0279998779297