Year	Percent
1991-01-01	52.1539993286133
1992-01-01	52.9440002441406
1993-01-01	54.1040000915527
1994-01-01	54.1349983215332
1995-01-01	56.2770004272461
1996-01-01	55.7529983520508
1997-01-01	55.2700004577637
1998-01-01	56.4879989624023
1999-01-01	57.3349990844727
2000-01-01	57.5690002441406
2001-01-01	57.5209999084473
2002-01-01	56.6110000610352
2003-01-01	55.7280006408691
2004-01-01	57.2500000000000
2005-01-01	57.2999992370605
2006-01-01	57.2280006408691
2007-01-01	54.7579994201660
2008-01-01	55.7439994812012
2009-01-01	55.6599998474121
2010-01-01	55.1500015258789
2011-01-01	57.1780014038086
2012-01-01	57.0880012512207
2013-01-01	57.3190002441406
2014-01-01	57.3680000305176
2015-01-01	57.4049987792969
2016-01-01	54.9910011291504
2017-01-01	55.2089996337891