"date","value"
1970-01-01,0.311405
1971-01-01,0.32518
1972-01-01,0.339565
1973-01-01,0.35458
1974-01-01,0.370265
1975-01-01,0.38664
1976-01-01,0.40374
1977-01-01,0.4216
1978-01-01,0.44025
1979-01-01,0.45972
1980-01-01,0.480055
1981-01-01,0.50129
1982-01-01,0.52346
1983-01-01,0.54661
1984-01-01,0.57079
1985-01-01,0.596035
1986-01-01,0.622395
1987-01-01,0.649925
1988-01-01,0.67867
1989-01-01,0.70869
1990-01-01,0.740035
1991-01-01,0.772765
1992-01-01,0.806945
1993-01-01,0.842635
1994-01-01,0.879905
1995-01-01,0.918825
1996-01-01,0.95946
1997-01-01,1.0019
1998-01-01,1.04622
1999-01-01,1.09249
2000-01-01,1.14081
2001-01-01,1.03352
2002-01-01,1.08867
2003-01-01,1.14676
2004-01-01,1.20796
2005-01-01,1.27242
2006-01-01,1.34031
2007-01-01,1.40159
2008-01-01,1.53409
2009-01-01,1.499