Year	Percent
1986-01-01	79.450
1987-01-01	78.400
1988-01-01	76.150
1989-01-01	74.850
1990-01-01	74.300
1991-01-01	73.950
1992-01-01	73.225
1993-01-01	73.225
1994-01-01	73.675
1995-01-01	74.125
1996-01-01	74.500
1997-01-01	74.325
1998-01-01	73.625
1999-01-01	73.400
2000-01-01	73.550
2001-01-01	73.875
2002-01-01	74.500
2003-01-01	73.750
2004-01-01	74.400
2005-01-01	75.050
2006-01-01	75.500
2007-01-01	75.525
2008-01-01	75.200
2009-01-01	74.500
2010-01-01	74.150
2011-01-01	74.225
2012-01-01	73.725
2013-01-01	73.525
2014-01-01	74.325
2015-01-01	74.300
2016-01-01	75.325
2017-01-01	76.225