Year	Percent
1999-01-01	78.675
2000-01-01	79.200
2001-01-01	79.400
2002-01-01	79.750
2003-01-01	80.125
2004-01-01	80.475
2005-01-01	80.325
2006-01-01	81.350
2007-01-01	81.550
2008-01-01	81.250
2009-01-01	79.050
2010-01-01	78.025
2011-01-01	79.475
2012-01-01	80.225
2013-01-01	81.400
2014-01-01	85.275
2015-01-01	86.850
2016-01-01	88.200
2017-01-01	90.100