Year	Ratio
1971-01-01	0.778599977493286
1974-01-01	0.806400001049042
1993-01-01	0.935020029544830
1994-01-01	0.958530008792877
2000-01-01	0.824949979782104
2001-01-01	0.967069983482361
2002-01-01	0.950349986553192
2003-01-01	0.983799993991852
2005-01-01	0.965680003166199
2008-01-01	0.963069975376129
2009-01-01	0.972150027751923
2010-01-01	0.986150026321411
2011-01-01	0.995580017566681
2012-01-01	0.993640005588531
2015-01-01	0.992269992828369