Year	Ratio
1970-01-01	0.97485
1971-01-01	0.97534
1972-01-01	0.97361
1973-01-01	0.97973
1974-01-01	0.97771
1975-01-01	0.97647
1976-01-01	0.98020
1977-01-01	0.98154
1978-01-01	0.98210
1979-01-01	0.98638
1980-01-01	0.99034
1981-01-01	0.98972
1982-01-01	0.98833
1983-01-01	0.98245
1984-01-01	0.98533
1985-01-01	0.98932
1986-01-01	0.98898
1987-01-01	0.98564
1988-01-01	0.98425
1989-01-01	0.98455
1990-01-01	0.98480
1991-01-01	0.98345
1992-01-01	0.98367
1993-01-01	0.98366
1994-01-01	0.98567
1995-01-01	0.98539
1996-01-01	0.98503
1997-01-01	0.98954
1998-01-01	0.99548
1999-01-01	0.99609
2000-01-01	0.98560
2001-01-01	0.99006
2002-01-01	0.99306
2003-01-01	0.99170
2004-01-01	0.98956
2005-01-01	0.98715
2006-01-01	0.99267
2007-01-01	0.99043
2008-01-01	0.99220
2009-01-01	0.99474
2010-01-01	0.99295
2011-01-01	0.99897
2012-01-01	0.99498
2013-01-01	0.99848
2014-01-01	1.00017
2015-01-01	1.00124
2016-01-01	1.00119