Year	Percent
1991-01-01	57.2080001831055
1992-01-01	56.2109985351563
1993-01-01	55.7709999084473
1994-01-01	56.9449996948242
1995-01-01	58.2789993286133
1996-01-01	58.2430000305176
1997-01-01	58.0089988708496
1998-01-01	58.3479995727539
1999-01-01	58.6609992980957
2000-01-01	59.3810005187988
2001-01-01	59.2630004882813
2002-01-01	59.5530014038086
2003-01-01	60.0050010681152
2004-01-01	60.2029991149902
2005-01-01	61.2929992675781
2006-01-01	61.7869987487793
2007-01-01	62.4739990234375
2008-01-01	62.8400001525879
2009-01-01	61.8849983215332
2010-01-01	62.1189994812012
2011-01-01	62.2229995727539
2012-01-01	61.8429985046387
2013-01-01	61.3279991149902
2014-01-01	60.8349990844727
2015-01-01	61.1069984436035
2016-01-01	61.1809997558594
2017-01-01	61.1829986572266