Year	Percent
1986-01-01	51.950
1987-01-01	52.425
1988-01-01	51.100
1989-01-01	49.250
1990-01-01	49.950
1991-01-01	48.975
1992-01-01	48.750
1993-01-01	49.100
1994-01-01	50.750
1995-01-01	52.200
1996-01-01	53.575
1997-01-01	53.150
1998-01-01	52.650
1999-01-01	53.450
2000-01-01	53.950
2001-01-01	55.125
2002-01-01	55.775
2003-01-01	56.275
2004-01-01	57.075
2005-01-01	58.275
2006-01-01	58.725
2007-01-01	59.275
2008-01-01	59.425
2009-01-01	58.300
2010-01-01	57.700
2011-01-01	58.275
2012-01-01	57.975
2013-01-01	58.550
2014-01-01	59.550
2015-01-01	59.650
2016-01-01	61.000
2017-01-01	61.975