Year	Percent
1998-01-01	22.875
1999-01-01	23.200
2000-01-01	22.375
2001-01-01	23.150
2002-01-01	25.900
2003-01-01	28.425
2004-01-01	29.400
2005-01-01	30.850
2006-01-01	32.100
2007-01-01	33.500
2008-01-01	34.425
2009-01-01	35.025
2010-01-01	35.475
2011-01-01	37.150
2012-01-01	39.050
2013-01-01	41.425
2014-01-01	43.825
2015-01-01	45.925
2016-01-01	49.300
2017-01-01	52.975