Year	Percent
1998-01-01	34.475
1999-01-01	35.875
2000-01-01	35.425
2001-01-01	36.325
2002-01-01	35.675
2003-01-01	34.750
2004-01-01	37.250
2005-01-01	37.625
2006-01-01	37.300
2007-01-01	36.825
2008-01-01	37.075
2009-01-01	37.400
2010-01-01	38.025
2011-01-01	38.400
2012-01-01	39.600
2013-01-01	37.275
2014-01-01	36.025
2015-01-01	34.975
2016-01-01	33.050
2017-01-01	30.725