Year	Percent
1999-01-01	86.325
2000-01-01	85.875
2001-01-01	83.750
2002-01-01	85.525
2003-01-01	85.050
2004-01-01	81.900
2005-01-01	81.050
2006-01-01	78.575
2007-01-01	76.975
2008-01-01	77.850
2009-01-01	74.425
2010-01-01	74.525
2011-01-01	76.275
2012-01-01	73.525
2013-01-01	73.025
2014-01-01	68.900
2015-01-01	67.075
2016-01-01	64.800
2017-01-01	60.475