Year	Ratio
1976-01-01	0.683059990406036
1977-01-01	0.715160012245178
1978-01-01	0.752780020236969
1979-01-01	0.743589997291565
1980-01-01	0.719439983367920
1981-01-01	0.679669976234436
1982-01-01	0.665199995040894
1983-01-01	0.671509981155396
1984-01-01	0.679859995841980
1985-01-01	0.696430027484894
1986-01-01	0.694729983806610
1987-01-01	0.727029979228973
1988-01-01	0.733340024948120
1989-01-01	0.742919981479645
1990-01-01	0.736760020256042
1991-01-01	0.750899970531464
1992-01-01	0.773620009422302
1993-01-01	0.787819981575012
1994-01-01	0.830640017986298
1995-01-01	0.852989971637726
1996-01-01	0.874260008335114
1997-01-01	0.879649996757507
2001-01-01	0.934989988803864
2003-01-01	0.943729996681213
2006-01-01	0.992340028285980
2007-01-01	1.001539945602420
2008-01-01	1.014979958534240
2009-01-01	1.027989983558650
2010-01-01	0.998359978199005
2011-01-01	1.003139972686770
2012-01-01	1.009039998054500
2013-01-01	1.018180012702940