Year	Ratio
1971-01-01	0.986320018768311
1972-01-01	0.990409970283508
1973-01-01	0.992209970951080
1974-01-01	0.992219984531403
1975-01-01	0.989950001239777
1976-01-01	0.994660019874573
1977-01-01	0.998470008373261
1978-01-01	0.997879981994629
1979-01-01	0.998220026493073
1980-01-01	0.993189990520477
1981-01-01	0.995949983596802
1982-01-01	0.999960005283356
1983-01-01	0.999509990215302
1984-01-01	0.998910009860992
1985-01-01	0.997240006923676
1986-01-01	0.996209979057312
1987-01-01	0.992299973964691
1988-01-01	0.992089986801147
1989-01-01	0.985949993133545
1990-01-01	0.981599986553192
1991-01-01	0.979420006275177
1992-01-01	0.977550029754639
1993-01-01	0.980239987373352
1994-01-01	0.998199999332428
1995-01-01	0.987070024013519
1996-01-01	0.979149997234344
1997-01-01	0.975459992885590
1998-01-01	0.972360014915466
1999-01-01	0.971279978752136
2000-01-01	0.972880005836487
2001-01-01	0.975069999694824
2002-01-01	0.982519984245300
2003-01-01	0.985080003738403
2004-01-01	0.987609982490540
2005-01-01	0.989950001239777
2006-01-01	0.986429989337921
2007-01-01	0.988020002841949
2008-01-01	0.994910001754761
2009-01-01	0.998489975929260
2010-01-01	0.996680021286011
2011-01-01	0.994870007038116
2012-01-01	0.991379976272583
2013-01-01	0.991010010242462
2014-01-01	0.992160022258759
2015-01-01	0.989610016345978
2016-01-01	0.989260017871857