Year	Ratio
1971-01-01	0.901139974594116
1976-01-01	0.889810025691986
1981-01-01	0.897660017013550
1982-01-01	0.911849975585938
1983-01-01	0.905130028724670
1984-01-01	0.905539989471436
1985-01-01	0.927659988403320
1986-01-01	0.912199974060059
1987-01-01	0.902570009231567
1988-01-01	0.909120023250580
1989-01-01	0.923259973526001
1990-01-01	0.914640009403229
1991-01-01	0.922699987888336
1992-01-01	0.923500001430511
1993-01-01	0.930400013923645
1994-01-01	0.936829984188080
1995-01-01	0.939140021800995
1996-01-01	0.945230007171631
1997-01-01	0.953400015830994
1998-01-01	0.945990025997162
1999-01-01	0.954739987850189
2000-01-01	0.959370017051697
2001-01-01	0.959190011024475
2002-01-01	0.951460003852844
2003-01-01	0.948480010032654
2004-01-01	0.944930016994476
2005-01-01	0.951629996299744
2006-01-01	0.960089981555939
2007-01-01	0.960500001907349
2008-01-01	0.957849979400635
2009-01-01	0.955030024051666
2010-01-01	0.960650026798248
2011-01-01	0.961000025272369
2012-01-01	0.962620019912720
2013-01-01	0.966050028800964
2014-01-01	0.963100016117096
2015-01-01	0.964850008487701
2016-01-01	0.961210012435913