Year	Ratio
1970-01-01	0.165560007095337
1972-01-01	0.153490006923676
1973-01-01	0.185460001230240
1974-01-01	0.162420004606247
1975-01-01	0.165000006556511
1976-01-01	0.165079995989800
1977-01-01	0.264979988336563
1978-01-01	0.236560001969337
1979-01-01	0.186259999871254
1986-01-01	0.173289999365807
1990-01-01	0.476170003414154
2003-01-01	0.281720012426376
2004-01-01	0.280270010232925
2009-01-01	0.235430002212524
2011-01-01	0.343710005283356
2014-01-01	0.275200009346008