Year	Percent
1999-01-01	33.775
2000-01-01	36.400
2001-01-01	35.125
2002-01-01	35.975
2003-01-01	37.825
2004-01-01	39.050
2005-01-01	41.725
2006-01-01	40.900
2007-01-01	42.850
2008-01-01	42.875
2009-01-01	42.900
2010-01-01	45.575
2011-01-01	45.975
2012-01-01	46.000
2013-01-01	47.725
2014-01-01	48.450
2015-01-01	48.850
2016-01-01	50.750
2017-01-01	53.825