Year	Ratio
1971-01-01	0.976220011711121
1972-01-01	0.976490020751953
1973-01-01	1.015519976615910
1974-01-01	1.031649947166440
1975-01-01	1.041249990463260
1976-01-01	1.038100004196170
1977-01-01	0.989369988441467
1978-01-01	1.024580001831050
1979-01-01	1.011610031127930
2004-01-01	0.981209993362427
2005-01-01	0.973860025405884
2007-01-01	1.012529969215390
2014-01-01	0.991249978542328
2015-01-01	1.002949953079220