Year	Ratio
1971-01-01	0.627170026302338
1972-01-01	0.655920028686523
1973-01-01	0.670459985733032
1974-01-01	0.676980018615723
1975-01-01	0.685559988021851
1976-01-01	0.696759998798370
1977-01-01	0.713769972324371
1978-01-01	0.721459984779358
1979-01-01	0.735660016536713
1980-01-01	0.745109975337982
1981-01-01	0.753769993782043
1982-01-01	0.758979976177216
1983-01-01	0.768000006675720
1984-01-01	0.774950027465820
1985-01-01	0.787010014057159
1986-01-01	0.804489970207214
1987-01-01	0.819090008735657
1988-01-01	0.827740013599396
1989-01-01	0.836530029773712
1990-01-01	0.841050028800964
1991-01-01	0.846360027790070
1992-01-01	0.856109976768494
1993-01-01	0.864080011844635
1994-01-01	0.875029981136322
1995-01-01	0.882979989051819
1996-01-01	0.892319977283478
1997-01-01	0.899160027503967
1998-01-01	0.906599998474121
1999-01-01	0.912440001964569
2000-01-01	0.916350007057190
2001-01-01	0.917840003967285
2002-01-01	0.924019992351532
2003-01-01	0.923080027103424
2004-01-01	0.925180017948151
2005-01-01	0.924399971961975
2006-01-01	0.925859987735748
2007-01-01	0.933279991149902
2008-01-01	0.935989975929260
2009-01-01	0.935299992561340
2010-01-01	0.936850011348724
2011-01-01	0.937699973583221
2012-01-01	0.943729996681213
2013-01-01	0.947660028934479
2014-01-01	0.950179994106293
2015-01-01	0.951499998569489
2016-01-01	0.948909997940063