Year	Percent
1998-01-01	55.225
1999-01-01	55.300
2000-01-01	52.700
2001-01-01	48.700
2002-01-01	47.025
2003-01-01	44.700
2004-01-01	44.400
2005-01-01	43.100
2006-01-01	41.150
2007-01-01	40.875
2008-01-01	39.400
2009-01-01	41.300
2010-01-01	39.925
2011-01-01	38.625
2012-01-01	38.375
2013-01-01	38.500
2014-01-01	38.100
2015-01-01	36.800
2016-01-01	34.875
2017-01-01	32.475