Year	Percent
1998-01-01	47.725
1999-01-01	46.975
2000-01-01	46.325
2001-01-01	47.325
2002-01-01	47.700
2003-01-01	45.200
2004-01-01	43.175
2005-01-01	42.100
2006-01-01	41.650
2007-01-01	41.325
2008-01-01	40.875
2009-01-01	38.725
2010-01-01	36.125
2011-01-01	38.175
2012-01-01	37.075
2013-01-01	35.025
2014-01-01	34.275
2015-01-01	33.500
2016-01-01	33.175
2017-01-01	34.000