Year	Percent
1991-01-01	59.0130004882813
1992-01-01	58.9659996032715
1993-01-01	58.8110008239746
1994-01-01	58.7500000000000
1995-01-01	58.7459983825684
1996-01-01	58.4659996032715
1997-01-01	58.3019981384277
1998-01-01	58.2260017395020
1999-01-01	58.2050018310547
2000-01-01	58.5320014953613
2001-01-01	58.8359985351563
2002-01-01	59.1459999084473
2003-01-01	59.4920005798340
2004-01-01	59.8680000305176
2005-01-01	60.3059997558594
2006-01-01	60.6650009155273
2007-01-01	61.0870018005371
2008-01-01	61.5559997558594
2009-01-01	62.0139999389648
2010-01-01	62.2820014953613
2011-01-01	62.9099998474121
2012-01-01	63.2500000000000
2013-01-01	63.5800018310547
2014-01-01	63.7970008850098
2015-01-01	63.9420013427734
2016-01-01	63.9350013732910
2017-01-01	63.6990013122559