Year	Ratio
1970-01-01	0.453099995851517
1971-01-01	0.473089993000031
1972-01-01	0.506070017814636
1973-01-01	0.529060006141663
1974-01-01	0.551360011100769
1975-01-01	0.585650026798248
1980-01-01	0.701789975166321
1981-01-01	0.718010008335114
1982-01-01	0.711489975452423
1983-01-01	0.717230021953583
1984-01-01	0.749300003051758
1985-01-01	0.749499976634979
1986-01-01	0.783900022506714
1987-01-01	0.791119992733002
1988-01-01	0.799000024795532
1999-01-01	0.955410003662109
2000-01-01	0.950630009174347
2001-01-01	0.938250005245209
2002-01-01	0.955150008201599
2003-01-01	1.023720026016240
2004-01-01	0.933239996433258
2005-01-01	0.954240024089813
2006-01-01	0.933920025825500
2007-01-01	0.874620020389557
2008-01-01	0.916209995746613
2009-01-01	0.904129981994629