Year	Ratio
1970-01-01	0.72738
1971-01-01	0.72778
1972-01-01	0.72863
1973-01-01	0.73002
1974-01-01	0.73790
1975-01-01	0.74468
1976-01-01	0.74426
1977-01-01	0.74770
1978-01-01	0.76107
1979-01-01	0.77406
1980-01-01	0.76565
1981-01-01	0.75576
1982-01-01	0.75177
1983-01-01	0.76504
1984-01-01	0.75521
1985-01-01	0.74765
1986-01-01	0.77361
1987-01-01	0.78559
1988-01-01	0.79174
1989-01-01	0.79991
1990-01-01	0.80283
1991-01-01	0.80932
1992-01-01	0.81696
1993-01-01	0.82270
1994-01-01	0.84011
1995-01-01	0.84928
1996-01-01	0.85823
1997-01-01	0.86993
1998-01-01	0.88576
1999-01-01	0.89988
2000-01-01	0.90574
2001-01-01	0.90926
2002-01-01	0.91615
2003-01-01	0.93315
2004-01-01	0.93598
2005-01-01	0.94597
2006-01-01	0.95328
2007-01-01	0.96135
2008-01-01	0.97068
2009-01-01	0.98370
2010-01-01	0.97690
2011-01-01	0.98001
2012-01-01	0.98367
2013-01-01	0.99748
2014-01-01	1.00310
2015-01-01	1.00125
2016-01-01	1.00288