Year	Ratio
1971-01-01	0.347909986972809
1972-01-01	0.355170011520386
1973-01-01	0.372339993715286
1974-01-01	0.383980005979538
1975-01-01	0.394470006227493
1976-01-01	0.360509991645813
1977-01-01	0.351379990577698
1978-01-01	0.333730012178421
1979-01-01	0.322100013494492
1980-01-01	0.310530006885529
1982-01-01	0.358759999275208
1983-01-01	0.370429992675781
1984-01-01	0.410089999437332
1985-01-01	0.472059994935989
1986-01-01	0.444460004568100
1987-01-01	0.442959994077683
1988-01-01	0.443269997835159
1989-01-01	0.452499985694885
1990-01-01	0.469680011272430
1991-01-01	0.488889992237091
1992-01-01	0.516539990901947
1993-01-01	0.579349994659424
1994-01-01	0.562349975109100
1995-01-01	0.571770012378693
1996-01-01	0.574100017547607
1997-01-01	0.637369990348816
1998-01-01	0.569060027599335
1999-01-01	0.572470009326935
2000-01-01	0.583469986915588
2001-01-01	0.594340026378632
2002-01-01	0.605480015277863
2003-01-01	0.613059997558594
2004-01-01	0.626150012016296
2005-01-01	0.640429973602295
2006-01-01	0.662299990653992
2007-01-01	0.686479985713959
2008-01-01	0.708880007266998
2009-01-01	0.726390004158020
2010-01-01	0.743879973888397
2011-01-01	0.749650001525879
2012-01-01	0.753260016441345
2013-01-01	0.757969975471497
2014-01-01	0.762679994106293
2015-01-01	0.770250022411346