Year	Percent
1999-01-01	19.925
2000-01-01	22.875
2001-01-01	24.200
2002-01-01	26.400
2003-01-01	29.775
2004-01-01	32.025
2005-01-01	34.325
2006-01-01	34.525
2007-01-01	33.700
2008-01-01	32.575
2009-01-01	34.100
2010-01-01	36.450
2011-01-01	38.825
2012-01-01	39.475
2013-01-01	41.250
2014-01-01	44.575
2015-01-01	48.100
2016-01-01	52.150
2017-01-01	53.575