Year	Percent
1991-01-01	53.6699981689453
1992-01-01	52.3849983215332
1993-01-01	51.1069984436035
1994-01-01	48.6809997558594
1995-01-01	48.4049987792969
1996-01-01	48.1010017395020
1997-01-01	48.1110000610352
1998-01-01	48.1539993286133
1999-01-01	48.9070014953613
2000-01-01	49.5919990539551
2001-01-01	48.5919990539551
2002-01-01	47.6170005798340
2003-01-01	46.6279983520508
2004-01-01	48.1590003967285
2005-01-01	49.6980018615723
2006-01-01	52.2220001220703
2007-01-01	52.3790016174316
2008-01-01	52.5369987487793
2009-01-01	52.9580001831055
2010-01-01	49.5079994201660
2011-01-01	53.1739997863770
2012-01-01	56.2420005798340
2013-01-01	58.6419982910156
2014-01-01	58.9889984130859
2015-01-01	59.3330001831055
2016-01-01	59.3479995727539
2017-01-01	59.4090003967285