Year	Ratio
1970-01-01	0.270420014858246
1971-01-01	0.245429992675781
1972-01-01	0.307370007038116
1973-01-01	0.310380011796951
1975-01-01	0.275929987430573
1979-01-01	0.372850000858307
1987-01-01	0.296389997005463
1999-01-01	0.239950001239777
2000-01-01	0.553149998188019
2010-01-01	0.532930016517639
2012-01-01	0.631460011005402