Year	Ratio
1971-01-01	0.0565299987792969
1972-01-01	0.0683799982070923
1974-01-01	0.1031000018119810
2007-01-01	0.3505100011825560
2008-01-01	0.3552100062370300
2009-01-01	0.3104400038719180
2011-01-01	0.4469999969005580
2012-01-01	0.5521699786186220
2013-01-01	0.4553099870681760