Year	Percent
1991-01-01	17.6040000915527
1992-01-01	17.6229991912842
1993-01-01	17.6819992065430
1994-01-01	17.6760005950928
1995-01-01	17.6900005340576
1996-01-01	17.6849994659424
1997-01-01	17.7119998931885
1998-01-01	17.7280006408691
1999-01-01	17.7479991912842
2000-01-01	17.7119998931885
2001-01-01	17.6849994659424
2002-01-01	17.6630001068115
2003-01-01	17.6889991760254
2004-01-01	17.6469993591309
2005-01-01	17.6630001068115
2006-01-01	17.7110004425049
2007-01-01	17.7240009307861
2008-01-01	17.7140007019043
2009-01-01	17.6480007171631
2010-01-01	17.6930007934570
2011-01-01	17.7619991302490
2012-01-01	17.7469997406006
2013-01-01	17.7749996185303
2014-01-01	17.8029994964600
2015-01-01	17.8320007324219
2016-01-01	17.9500007629395
2017-01-01	17.7989997863770