Year	Ratio
1971-01-01	0.365280002355576
1972-01-01	0.406360000371933
1973-01-01	0.486299991607666
1977-01-01	0.494749993085861
1978-01-01	0.533060014247894
1979-01-01	0.568470001220703
1980-01-01	0.631619989871979
1981-01-01	0.642799973487854
1986-01-01	0.711790025234222
1988-01-01	0.711570024490356
1990-01-01	0.685490012168884
1992-01-01	0.657999992370605
1993-01-01	0.632319986820221
1994-01-01	0.648060023784637
1995-01-01	0.661909997463226
1996-01-01	0.666260004043579
1997-01-01	0.668649971485138
1998-01-01	0.689499974250793
1999-01-01	0.694230020046234
2000-01-01	0.701499998569489
2001-01-01	0.714139997959137
2002-01-01	0.725480020046234
2003-01-01	0.737580001354218
2004-01-01	0.747910022735596
2005-01-01	0.754930019378662
2006-01-01	0.773180007934570
2007-01-01	0.782850027084351
2008-01-01	0.799769997596741
2009-01-01	0.814320027828217
2010-01-01	0.828890025615692
2011-01-01	0.847429990768433
2012-01-01	0.868929982185364
2013-01-01	0.887329995632172
2014-01-01	0.912000000476837
2015-01-01	0.924960017204285
2016-01-01	0.928810000419617