Year	Percent
1991-01-01	79.0920028686523
1992-01-01	79.0619964599609
1993-01-01	79.0520019531250
1994-01-01	78.9449996948242
1995-01-01	78.8880004882813
1996-01-01	78.8690032958984
1997-01-01	78.8349990844727
1998-01-01	78.7969970703125
1999-01-01	78.7170028686523
2000-01-01	78.5970001220703
2001-01-01	78.5179977416992
2002-01-01	78.3880004882813
2003-01-01	78.2480010986328
2004-01-01	78.0849990844727
2005-01-01	77.7399978637695
2006-01-01	77.6630020141602
2007-01-01	77.6029968261719
2008-01-01	77.5569992065430
2009-01-01	77.5449981689453
2010-01-01	77.4990005493164
2011-01-01	77.5059967041016
2012-01-01	77.5459976196289
2013-01-01	77.5739974975586
2014-01-01	77.6269989013672
2015-01-01	77.6559982299805
2016-01-01	77.6289978027344
2017-01-01	77.7480010986328