Year	Percent
1999-01-01	40.225
2000-01-01	39.850
2001-01-01	40.400
2002-01-01	40.300
2003-01-01	39.425
2004-01-01	39.525
2005-01-01	38.650
2006-01-01	37.950
2007-01-01	38.350
2008-01-01	38.825
2009-01-01	38.775
2010-01-01	38.100
2011-01-01	37.625
2012-01-01	36.300
2013-01-01	35.300
2014-01-01	33.025
2015-01-01	31.350
2016-01-01	29.875
2017-01-01	28.825