Year	Percent
1998-01-01	44.100
1999-01-01	42.700
2000-01-01	41.100
2001-01-01	42.200
2002-01-01	42.450
2003-01-01	41.400
2004-01-01	38.975
2005-01-01	38.100
2006-01-01	37.650
2007-01-01	37.850
2008-01-01	38.075
2009-01-01	37.225
2010-01-01	34.200
2011-01-01	35.900
2012-01-01	34.900
2013-01-01	33.750
2014-01-01	33.825
2015-01-01	32.800
2016-01-01	31.250
2017-01-01	32.350