Year	Percent
1999-01-01	71.200
2000-01-01	71.025
2001-01-01	70.975
2002-01-01	71.625
2003-01-01	72.050
2004-01-01	70.400
2005-01-01	71.450
2006-01-01	72.375
2007-01-01	73.500
2008-01-01	73.875
2009-01-01	74.325
2010-01-01	74.425
2011-01-01	74.550
2012-01-01	75.100
2013-01-01	75.500
2014-01-01	75.400
2015-01-01	75.525
2016-01-01	76.200
2017-01-01	76.425