Year	Percent
1998-01-01	39.950
1999-01-01	38.500
2000-01-01	37.975
2001-01-01	38.250
2002-01-01	36.425
2003-01-01	34.600
2004-01-01	32.300
2005-01-01	31.600
2006-01-01	30.775
2007-01-01	30.825
2008-01-01	30.450
2009-01-01	28.850
2010-01-01	27.650
2011-01-01	27.200
2012-01-01	26.025
2013-01-01	25.700
2014-01-01	24.400
2015-01-01	22.325
2016-01-01	22.250
2017-01-01	23.000