Year	Ratio
1971-01-01	0.307119995355606
1972-01-01	0.292140007019043
1973-01-01	0.276760011911392
1974-01-01	0.349469989538193
1975-01-01	0.431389987468719
1976-01-01	0.510510027408600
1977-01-01	0.492159992456436
1978-01-01	0.504149973392487
1979-01-01	0.501559972763062
1980-01-01	0.467359989881516
1981-01-01	0.488370001316071
1982-01-01	0.465119987726212
1983-01-01	0.474489986896515
1984-01-01	0.481070011854172
1985-01-01	0.412330001592636
1986-01-01	0.572619974613190
1987-01-01	0.640919983386993
1988-01-01	0.660210013389587
1989-01-01	0.619239985942841
1999-01-01	0.542029976844788
2000-01-01	0.539020001888275
2002-01-01	0.540950000286102
2004-01-01	0.596530020236969
2005-01-01	0.597379982471466