Year	Ratio
1971-01-01	0.677259981632233
1972-01-01	0.656910002231598
1973-01-01	0.723969995975494
1974-01-01	0.788950026035309
1975-01-01	0.831669986248016
1976-01-01	0.896570026874542
1977-01-01	0.937839984893799
1978-01-01	0.963720023632050
1979-01-01	0.985960006713867
1980-01-01	0.975809991359711
1981-01-01	0.954949975013733
1982-01-01	0.955060005187988
1983-01-01	0.954280018806458
1984-01-01	0.953899979591370
1985-01-01	0.952430009841919
1986-01-01	0.968270003795624
1987-01-01	0.957790017127991
1988-01-01	0.948029994964600
1989-01-01	0.946200013160706
1990-01-01	0.950969994068146
1991-01-01	0.961130023002625
1992-01-01	0.970059990882874
1993-01-01	0.985629975795746
1994-01-01	0.983299970626831
1995-01-01	0.979480028152466
1996-01-01	0.986450016498566
1997-01-01	0.981270015239716
1998-01-01	0.989380002021790
2007-01-01	0.999989986419678
2009-01-01	1.013659954071040
2010-01-01	1.020670056343080
2011-01-01	0.992259979248047
2012-01-01	1.008870005607600
2013-01-01	1.024090051651000
2014-01-01	1.026520013809200
2015-01-01	1.013370037078860
2016-01-01	0.965409994125366