Year	Percent
1979-01-01	63.8475070666667
1980-01-01	66.1752403916667
1981-01-01	65.5172614083333
1982-01-01	65.3766398166667
1983-01-01	65.8717571250000
1984-01-01	66.1680818833334
1985-01-01	66.7544239666667
1986-01-01	67.9826763000000
1987-01-01	67.6758093000000
1988-01-01	67.3231878916667
1989-01-01	68.7116116666667
1990-01-01	68.8554666666667
1991-01-01	66.6875661916667
1992-01-01	66.4847506250000
1993-01-01	65.7210519916667
1994-01-01	68.1417769000000
1995-01-01	69.5552420166667
1996-01-01	69.4800437750000
1997-01-01	67.5146923583333
1998-01-01	67.6055961166667
1999-01-01	67.9666101500000
2000-01-01	68.4536057333333
2001-01-01	69.0657662000000
2002-01-01	68.2234087750000
2003-01-01	69.0098159750000
2004-01-01	69.0749533916667
2005-01-01	69.5674937833333
2006-01-01	69.4867312916667
2007-01-01	69.6901962416667
2008-01-01	69.4769506416667
2009-01-01	67.7320432333334
2010-01-01	67.1904502833333
2011-01-01	67.4718013166667
2012-01-01	66.7839422583334
2013-01-01	66.2646061000000
2014-01-01	66.2517941416667
2015-01-01	66.7234971916667
2016-01-01	66.3608997333333
2017-01-01	66.3408160333334