Year	Percent
1979-01-01	86.6285642833333
1980-01-01	86.7047405500000
1981-01-01	86.5318375500000
1982-01-01	86.0297385500000
1983-01-01	85.3083664333333
1984-01-01	84.8644290833333
1985-01-01	84.4426112000000
1986-01-01	84.7923483750000
1987-01-01	84.3554637416667
1988-01-01	84.3397715583334
1989-01-01	84.6940189750000
1990-01-01	85.0048764250000
1991-01-01	84.1781947416666
1992-01-01	83.7518165083333
1993-01-01	83.4139685750000
1994-01-01	83.5061302333333
1995-01-01	83.8178957916667
1996-01-01	83.6955505916666
1997-01-01	83.0864624416667
1998-01-01	82.8579042333333
1999-01-01	82.4967693666667
2000-01-01	82.3264043750000
2001-01-01	82.1838973500000
2002-01-01	82.1511217166667
2003-01-01	81.9693142166667
2004-01-01	82.0133412583334
2005-01-01	82.6173180166667
2006-01-01	82.7440287166666
2007-01-01	82.9645131750000
2008-01-01	83.0454399750000
2009-01-01	82.6127329833333
2010-01-01	82.8972562916667
2011-01-01	82.8430326833333
2012-01-01	82.4799555750000
2013-01-01	82.3809802583333
2014-01-01	82.1174262666667
2015-01-01	82.6884952250000
2016-01-01	82.3303075500000
2017-01-01	82.6049377833333