Year	Percent
1999-01-01	50.875
2000-01-01	49.475
2001-01-01	49.800
2002-01-01	47.475
2003-01-01	44.900
2004-01-01	42.875
2005-01-01	40.750
2006-01-01	39.675
2007-01-01	38.850
2008-01-01	37.825
2009-01-01	37.150
2010-01-01	36.400
2011-01-01	37.175
2012-01-01	37.075
2013-01-01	37.550
2014-01-01	38.050
2015-01-01	38.275
2016-01-01	39.750
2017-01-01	39.575