Year	Percent
1991-01-01	50.8180007934570
1992-01-01	50.6279983520508
1993-01-01	48.7210006713867
1994-01-01	48.3740005493164
1995-01-01	48.1500015258789
1996-01-01	48.2350006103516
1997-01-01	48.8610000610352
1998-01-01	48.7949981689453
1999-01-01	48.2890014648438
2000-01-01	48.4500007629395
2001-01-01	48.0349998474121
2002-01-01	48.4129981994629
2003-01-01	48.2150001525879
2004-01-01	47.9939994812012
2005-01-01	47.7910003662109
2006-01-01	47.7420005798340
2007-01-01	48.3730010986328
2008-01-01	47.8709983825684
2009-01-01	47.0299987792969
2010-01-01	46.5639991760254
2011-01-01	47.9259986877441
2012-01-01	49.7229995727539
2013-01-01	45.2610015869141
2014-01-01	44.8510017395020
2015-01-01	46.8089981079102
2016-01-01	47.7130012512207
2017-01-01	48.2949981689453