Year	Percent
1991-01-01	3.81200003623962
1992-01-01	3.77800011634827
1993-01-01	3.78399991989136
1994-01-01	3.77699995040894
1995-01-01	3.75000000000000
1996-01-01	3.72399997711182
1997-01-01	3.66599988937378
1998-01-01	3.62599992752075
1999-01-01	3.70499992370605
2000-01-01	3.76099991798401
2001-01-01	3.85899996757507
2002-01-01	3.92700004577637
2003-01-01	4.04799985885620
2004-01-01	4.92199993133545
2005-01-01	5.84200000762939
2006-01-01	3.75799989700317
2007-01-01	4.85300016403198
2008-01-01	5.38399982452393
2009-01-01	5.88299989700317
2010-01-01	6.45100021362305
2011-01-01	6.95699977874756
2012-01-01	7.47900009155273
2013-01-01	7.99700021743774
2014-01-01	8.56099987030029
2015-01-01	8.55900001525879
2016-01-01	8.55200004577637
2017-01-01	8.56299972534180