year  ismidx-jjas
1948   0.689
1949  -1.640
1950  -0.285
1951  -0.713
1952   0.202
1953  -0.031
1954   1.171
1955   0.030
1956   1.370
1957   0.482
1958   1.371
1959   2.048
1960   0.652
1961   1.651
1962  -0.188
1963  -0.620
1964   0.130
1965  -2.091
1966  -1.577
1967   0.225
1968  -0.657
1969  -0.563
1970   1.495
1971  -0.107
1972  -2.288
1973   0.984
1974  -1.533
1975   1.463
1976  -0.543
1977   0.156
1978   1.036
1979  -1.301
1980   0.989
1981   0.079
1982  -0.735
1983   1.103
1984  -0.725
1985  -1.072
1986  -0.519
1987  -2.317
1988   0.677
1989  -0.041
1990   0.292
1991   0.045
1992   0.405
1993   0.103
1994   1.261
1995  -0.459
1996   0.554
1997  -1.427
1998   0.661
1999  -0.786
2000   0.307
2001   0.009
2002  -1.052
2003   0.320
2004   0.007
2005   0.986
2006   0.866
2007   0.512
2008  -1.060