Year	Ratio
1970-01-01	0.532140016555786
1971-01-01	0.526419997215271
1972-01-01	0.491780012845993
1973-01-01	0.485210001468658
1974-01-01	0.486110001802444
1975-01-01	0.468609988689423
1976-01-01	0.435990005731583
1980-01-01	0.541299998760223
2001-01-01	0.976040005683899
2002-01-01	1.067849993705750
2003-01-01	1.070449948310850
2004-01-01	1.023480057716370
2005-01-01	1.025910019874570
2006-01-01	1.065320014953610