Year	Percent
1991-01-01	56.6699981689453
1992-01-01	56.2430000305176
1993-01-01	56.7270011901855
1994-01-01	58.3499984741211
1995-01-01	60.0919990539551
1996-01-01	60.9389991760254
1997-01-01	60.4220008850098
1998-01-01	59.4720001220703
1999-01-01	60.0040016174316
2000-01-01	60.7249984741211
2001-01-01	61.7999992370605
2002-01-01	62.5730018615723
2003-01-01	62.6710014343262
2004-01-01	63.7080001831055
2005-01-01	64.6149978637695
2006-01-01	65.1169967651367
2007-01-01	65.5289993286133
2008-01-01	65.1330032348633
2009-01-01	63.5530014038086
2010-01-01	63.0789985656738
2011-01-01	63.4920005798340
2012-01-01	63.0120010375977
2013-01-01	63.6780014038086
2014-01-01	64.7170028686523
2015-01-01	64.6630020141602
2016-01-01	65.7679977416992
2017-01-01	65.8339996337891