Year	Percent
1991-01-01	52.5729880899048
1992-01-01	51.7431893401467
1993-01-01	50.6429955973481
1994-01-01	50.1600602638356
1995-01-01	50.2525236243044
1996-01-01	50.1820791053492
1997-01-01	50.3449229916274
1998-01-01	50.6470697297632
1999-01-01	50.9634325545681
2000-01-01	51.2523612347892
2001-01-01	51.4540316950736
2002-01-01	51.2137010841931
2003-01-01	51.3072669104601
2004-01-01	51.2694891030239
2005-01-01	51.6957491568655
2006-01-01	52.3052638343101
2007-01-01	53.0153777397326
2008-01-01	53.3258978134865
2009-01-01	52.1900647280260
2010-01-01	51.8080355761699
2011-01-01	51.6899950982584
2012-01-01	51.4300094622176
2013-01-01	51.1903961099564
2014-01-01	51.5570075659870
2015-01-01	51.9875162106379
2016-01-01	52.5501298490930
2017-01-01	52.9340445980557