Year	Percent
1991-01-01	58.3120002746582
1992-01-01	58.3899993896484
1993-01-01	58.4169998168945
1994-01-01	58.5559997558594
1995-01-01	58.2490005493164
1996-01-01	57.8950004577637
1997-01-01	57.4550018310547
1998-01-01	57.1619987487793
1999-01-01	56.8790016174316
2000-01-01	56.4560012817383
2001-01-01	56.7410011291504
2002-01-01	56.9760017395020
2003-01-01	57.3580017089844
2004-01-01	57.6409988403320
2005-01-01	57.9529991149902
2006-01-01	56.9790000915527
2007-01-01	56.0419998168945
2008-01-01	54.9970016479492
2009-01-01	54.2150001525879
2010-01-01	53.3610000610352
2011-01-01	52.7099990844727
2012-01-01	52.0099983215332
2013-01-01	52.0970001220703
2014-01-01	52.1199989318848
2015-01-01	52.0660018920898
2016-01-01	52.0390014648438
2017-01-01	51.8930015563965