Year	Percent
1999-01-01	15.125
2000-01-01	15.775
2001-01-01	16.200
2002-01-01	16.425
2003-01-01	16.225
2004-01-01	15.950
2005-01-01	16.375
2006-01-01	15.925
2007-01-01	16.325
2008-01-01	15.700
2009-01-01	16.400
2010-01-01	17.375
2011-01-01	17.650
2012-01-01	18.550
2013-01-01	19.425
2014-01-01	18.900
2015-01-01	18.425
2016-01-01	17.350
2017-01-01	18.475