Year	Ratio
1970-01-01	0.930400013923645
1971-01-01	0.930999994277954
1972-01-01	0.927900016307831
1973-01-01	0.936890006065369
1974-01-01	0.950980007648468
1975-01-01	0.958400011062622
1976-01-01	0.965369999408722
1977-01-01	0.973760008811951
1978-01-01	0.984329998493195
1979-01-01	0.990159988403320
1980-01-01	0.992200016975403
1981-01-01	0.985329985618591
1982-01-01	0.986150026321411
1983-01-01	0.979730010032654
1984-01-01	0.984139978885651
1985-01-01	0.982320010662079
1986-01-01	0.987659990787506
1987-01-01	0.989000022411346
1988-01-01	0.990880012512207
1989-01-01	1.000000000000000
1990-01-01	0.994780004024506
1991-01-01	0.983820021152496
1992-01-01	0.977649986743927
1993-01-01	0.969959974288940
1994-01-01	0.972999989986420
1995-01-01	0.968689978122711
1996-01-01	0.963789999485016
1997-01-01	0.964820027351379
1998-01-01	0.953869998455048
1999-01-01	0.954289972782135
2000-01-01	0.944299995899200
2001-01-01	0.954200029373169
2002-01-01	0.933120012283325
2003-01-01	0.949819982051849
2004-01-01	0.936850011348724
2005-01-01	0.933239996433258
2006-01-01	0.928460001945496
2007-01-01	0.926949977874756
2009-01-01	0.915340006351471
2010-01-01	0.912199974060059
2011-01-01	0.892750024795532
2012-01-01	0.912240028381348
2013-01-01	0.911249995231628
2014-01-01	0.913749992847443
2015-01-01	0.912840008735657