Year	Ratio
1971-01-01	0.407680004835129
1972-01-01	0.407750010490417
1973-01-01	0.429859995841980
1974-01-01	0.450190007686615
1975-01-01	0.478670001029968
1976-01-01	0.500630021095276
1977-01-01	0.520759999752045
1978-01-01	0.505259990692139
1979-01-01	0.512369990348816
1980-01-01	0.508549988269806
1981-01-01	0.511569976806641
1982-01-01	0.515169978141785
1983-01-01	0.525179982185364
1984-01-01	0.534139990806580
1985-01-01	0.549109995365143
1986-01-01	0.561569988727570
1987-01-01	0.585709989070892
1988-01-01	0.616699993610382
1989-01-01	0.633189976215363
1990-01-01	0.652390003204346
1991-01-01	0.653299987316132
1992-01-01	0.710619986057281
1994-01-01	0.816039979457855
1995-01-01	0.826179981231689
1998-01-01	0.843630015850067
1999-01-01	0.845229983329773
2000-01-01	0.851440012454987
2001-01-01	0.851029992103577
2002-01-01	0.861890017986298
2003-01-01	0.879100024700165
2004-01-01	0.890349984169006
2005-01-01	0.892650008201599
2006-01-01	0.884920001029968
2007-01-01	0.882820010185242
2008-01-01	0.887579977512360
2009-01-01	0.889039993286133
2010-01-01	0.894590020179749
2011-01-01	0.897909998893738
2012-01-01	0.905219972133636
2013-01-01	0.917339980602264
2014-01-01	0.931129992008209
2015-01-01	0.941200017929077