Year	Percent
1991-01-01	55.1040000915527
1992-01-01	55.0979995727539
1993-01-01	55.7719993591309
1994-01-01	56.0989990234375
1995-01-01	56.3530006408691
1996-01-01	53.9309997558594
1997-01-01	56.2620010375977
1998-01-01	57.9090003967285
1999-01-01	57.1759986877441
2000-01-01	56.4300003051758
2001-01-01	57.8050003051758
2002-01-01	57.4700012207031
2003-01-01	57.5009994506836
2004-01-01	56.4500007629395
2005-01-01	58.3919982910156
2006-01-01	58.5839996337891
2007-01-01	60.1349983215332
2008-01-01	59.6259994506836
2009-01-01	57.2200012207031
2010-01-01	55.1279983520508
2011-01-01	55.6549987792969
2012-01-01	55.3339996337891
2013-01-01	56.0639991760254
2014-01-01	57.1870002746582
2015-01-01	56.4129981994629
2016-01-01	54.0810012817383
2017-01-01	54.6920013427734