Year	Ratio
1971-01-01	0.331510007381439
1972-01-01	0.339320003986359
1974-01-01	0.376489996910095
1984-01-01	0.563210010528564
1991-01-01	0.774150013923645
1992-01-01	0.844210028648376
1993-01-01	0.875440001487732
1994-01-01	0.843519985675812
1995-01-01	0.794950008392334
1996-01-01	0.756120026111603
1999-01-01	0.679600000381470
2000-01-01	0.672640025615692
2001-01-01	0.666019976139069
2002-01-01	0.627610027790070
2003-01-01	0.578689992427826
2004-01-01	0.577719986438751
2005-01-01	0.602100014686584
2006-01-01	0.634339988231659
2007-01-01	0.675599992275238
2008-01-01	0.731999993324280
2009-01-01	0.782800018787384
2010-01-01	0.830910027027130
2011-01-01	0.882709980010986
2012-01-01	0.903140008449554
2015-01-01	0.958869993686676