Year	Ratio
1970-01-01	0.981809973716736
1971-01-01	0.980679988861084
1972-01-01	0.985130012035370
1973-01-01	0.983169972896576
1974-01-01	0.976700007915497
1975-01-01	0.977540016174316
1976-01-01	0.979240000247955
1977-01-01	0.980040013790131
1978-01-01	0.980220019817352
1979-01-01	0.979219973087311
1980-01-01	0.979820013046265
1981-01-01	0.976760029792786
1982-01-01	0.973609983921051
1983-01-01	0.973580002784729
1984-01-01	0.980090022087097
1985-01-01	0.981809973716736
1986-01-01	0.987010002136230
1987-01-01	0.988919973373413
1988-01-01	0.994560003280640
1989-01-01	0.989780008792877
1990-01-01	0.981559991836548
1991-01-01	0.989669978618622
1992-01-01	0.989610016345978
1993-01-01	0.993759989738464
1994-01-01	0.995589971542358
1995-01-01	0.997070014476776
1996-01-01	0.996420025825500
1997-01-01	0.993350028991699
1998-01-01	0.995720028877258
1999-01-01	0.998329997062683
2000-01-01	1.001760005950930
2001-01-01	0.993960022926331
2002-01-01	0.995090007781982
2003-01-01	0.995050013065338
2004-01-01	0.992850005626678
2005-01-01	0.991760015487671
2006-01-01	0.992839992046356
2007-01-01	0.997290015220642
2008-01-01	0.997479975223541
2009-01-01	1.001530051231380
2010-01-01	1.003209948539730
2011-01-01	1.007220029830930
2012-01-01	1.007019996643070
2013-01-01	1.006659984588620
2014-01-01	1.003340005874630
2015-01-01	1.005360007286070
2016-01-01	1.007500052452090