Year	Percent
1968-01-01	85.5423674333366
1969-01-01	85.9081001033395
1970-01-01	85.0361671499023
1971-01-01	85.4367640244454
1972-01-01	84.5648187700606
1973-01-01	85.2113856937841
1974-01-01	84.6746745772100
1975-01-01	83.8043327861424
1976-01-01	83.1309298559223
1977-01-01	81.8676122753456
1978-01-01	81.6331437437862
1979-01-01	81.8984670796931
1980-01-01	82.3814807123277
1981-01-01	81.7930237498694
1982-01-01	81.3948925461416
1983-01-01	80.8403190036579
1984-01-01	79.7897913504366
1985-01-01	79.3714843823305
1986-01-01	78.9106369586223
1987-01-01	78.5504561967304
1988-01-01	78.7914784201901
1989-01-01	79.7062335243400
1990-01-01	80.7902166155188
1991-01-01	82.1698337408900
1992-01-01	82.3602404775079
1993-01-01	82.1087528778611
1994-01-01	81.2736852343236
1995-01-01	80.9748527247995
1996-01-01	80.7471967962761
1997-01-01	80.9085862814966
1998-01-01	79.7532707265523
1999-01-01	79.4752793211006
2000-01-01	78.4962615575778
2001-01-01	77.5605919505574
2002-01-01	76.9656262807105
2003-01-01	77.4213790432937
2004-01-01	78.2534448955801
2005-01-01	78.9543225317405
2006-01-01	80.0372655004650
2007-01-01	81.5376778860308
2008-01-01	81.4915106536584
2009-01-01	79.9752071571201
2010-01-01	79.1126040521692
2011-01-01	79.2286504352280
2012-01-01	78.8657689870676
2013-01-01	79.8681511987941
2014-01-01	81.5973588312893
2015-01-01	82.5435153937678
2016-01-01	83.5906898108319
2017-01-01	85.0598705438924