Year	Percent
1999-01-01	18.825
2000-01-01	20.150
2001-01-01	21.700
2002-01-01	22.350
2003-01-01	23.750
2004-01-01	24.950
2005-01-01	27.650
2006-01-01	28.925
2007-01-01	30.200
2008-01-01	31.175
2009-01-01	32.150
2010-01-01	33.100
2011-01-01	35.675
2012-01-01	36.000
2013-01-01	36.300
2014-01-01	37.800
2015-01-01	40.150
2016-01-01	42.725
2017-01-01	43.550