Year	Ratio
1971-01-01	0.205029994249344
1972-01-01	0.193990007042885
1977-01-01	0.251639991998672
1978-01-01	0.238159999251366
1980-01-01	0.230839997529984
1981-01-01	0.225730001926422
1982-01-01	0.227180004119873
1984-01-01	0.254319995641708
1985-01-01	0.262419998645782
1992-01-01	0.321680009365082
2006-01-01	0.458990007638931
2007-01-01	0.525539994239807
2008-01-01	0.541249990463257
2009-01-01	0.581939995288849
2010-01-01	0.589789986610413
2011-01-01	0.585039973258972
2012-01-01	0.586329996585846
2013-01-01	0.588310003280640
2014-01-01	0.595870018005371
2015-01-01	0.604659974575043
2016-01-01	0.601520001888275