Year	Percent
1991-01-01	60.0289993286133
1992-01-01	60.2610015869141
1993-01-01	60.3300018310547
1994-01-01	60.2299995422363
1995-01-01	60.2410011291504
1996-01-01	60.0919990539551
1997-01-01	60.0410003662109
1998-01-01	60.2550010681152
1999-01-01	60.1749992370605
2000-01-01	60.1040000915527
2001-01-01	60.1889991760254
2002-01-01	60.1419982910156
2003-01-01	60.0769996643066
2004-01-01	59.6899986267090
2005-01-01	59.7029991149902
2006-01-01	59.6419982910156
2007-01-01	59.9879989624023
2008-01-01	59.7340011596680
2009-01-01	60.0139999389648
2010-01-01	60.1030006408691
2011-01-01	60.7760009765625
2012-01-01	60.3889999389648
2013-01-01	60.1139984130859
2014-01-01	60.6689987182617
2015-01-01	60.4580001831055
2016-01-01	60.5579986572266
2017-01-01	60.8520011901855