Year	Percent
1999-01-01	76.125
2000-01-01	75.625
2001-01-01	75.875
2002-01-01	75.450
2003-01-01	75.100
2004-01-01	76.150
2005-01-01	75.950
2006-01-01	76.950
2007-01-01	76.400
2008-01-01	76.975
2009-01-01	76.825
2010-01-01	76.025
2011-01-01	76.150
2012-01-01	75.800
2013-01-01	75.625
2014-01-01	75.025
2015-01-01	75.275
2016-01-01	77.200
2017-01-01	76.100