Year	Percent
1991-01-01	66.0889968872070
1992-01-01	65.9020004272461
1993-01-01	65.6839981079102
1994-01-01	65.4530029296875
1995-01-01	65.2369995117188
1996-01-01	65.0199966430664
1997-01-01	64.8860015869141
1998-01-01	64.7419967651367
1999-01-01	64.6190032958984
2000-01-01	63.6189994812012
2001-01-01	62.5419998168945
2002-01-01	61.4490013122559
2003-01-01	60.3059997558594
2004-01-01	59.1590003967285
2005-01-01	58.0180015563965
2006-01-01	58.0769996643066
2007-01-01	58.2099990844727
2008-01-01	58.4319992065430
2009-01-01	57.8269996643066
2010-01-01	57.9609985351563
2011-01-01	58.0810012817383
2012-01-01	58.1220016479492
2013-01-01	58.0929985046387
2014-01-01	58.0419998168945
2015-01-01	57.9860000610352
2016-01-01	57.9039993286133
2017-01-01	57.9039993286133