Year	Ratio
1981-01-01	0.95399
1982-01-01	0.95416
1983-01-01	0.93921
1984-01-01	0.95454
1985-01-01	0.96167
1988-01-01	0.91164
1989-01-01	0.91235
1990-01-01	0.95777
1991-01-01	0.96428
1992-01-01	0.96704
1993-01-01	0.98046
1994-01-01	0.97410
1995-01-01	0.97548
1996-01-01	0.97456