Year	Percent
1991-01-01	59.8839988708496
1992-01-01	60.6699981689453
1993-01-01	60.9580001831055
1994-01-01	60.9319992065430
1995-01-01	59.4059982299805
1996-01-01	57.2179985046387
1997-01-01	56.4760017395020
1998-01-01	56.3779983520508
1999-01-01	56.6549987792969
2000-01-01	56.6370010375977
2001-01-01	58.4980010986328
2002-01-01	55.6689987182617
2003-01-01	57.4729995727539
2004-01-01	55.5859985351563
2005-01-01	54.6220016479492
2006-01-01	54.7630004882813
2007-01-01	55.0089988708496
2008-01-01	53.0830001831055
2009-01-01	52.9650001525879
2010-01-01	54.2779998779297
2011-01-01	56.0369987487793
2012-01-01	57.1180000305176
2013-01-01	56.9620018005371
2014-01-01	58.8349990844727
2015-01-01	59.9729995727539
2016-01-01	59.5600013732910
2017-01-01	59.7900009155273