Year	Percent
1999-01-01	76.225
2000-01-01	77.375
2001-01-01	76.625
2002-01-01	76.525
2003-01-01	76.500
2004-01-01	77.250
2005-01-01	78.300
2006-01-01	78.375
2007-01-01	79.675
2008-01-01	80.450
2009-01-01	79.750
2010-01-01	80.000
2011-01-01	79.350
2012-01-01	79.275
2013-01-01	79.050
2014-01-01	79.125
2015-01-01	78.525
2016-01-01	79.075
2017-01-01	79.525