Year	Percent
1999-01-01	77.075
2000-01-01	77.325
2001-01-01	77.075
2002-01-01	77.000
2003-01-01	77.825
2004-01-01	77.850
2005-01-01	78.725
2006-01-01	79.925
2007-01-01	80.150
2008-01-01	80.300
2009-01-01	80.275
2010-01-01	80.875
2011-01-01	81.250
2012-01-01	82.875
2013-01-01	83.300
2014-01-01	85.000
2015-01-01	85.800
2016-01-01	86.125
2017-01-01	86.825