1971 01 99.99 -99.99  20.80 
1971 02 99.99 -99.99  22.20 
1971 03 99.99 -99.99  28.10 
1971 04 99.99 -99.99  29.10 
1971 05 99.99 -99.99  33.80 
1971 06 99.99 -99.99  33.00 
1971 07 99.99 -99.99  32.59 
1971 08 99.99 -99.99  32.90 
1971 09 99.99 -99.99  30.90 
1971 10 99.99 -99.99  27.70 
1971 11 99.99 -99.99  23.50 
1971 12 99.99 -99.99  19.40 
1972 01 99.99 -99.99  20.00 
1972 02 99.99 -99.99  22.20 
1972 03 99.99 -99.99  26.90 
1972 04 99.99 -99.99  30.50 
1972 05 99.99 -99.99  34.20 
1972 06 99.99 -99.99  34.20 
1972 07 99.99 -99.99  34.20 
1972 08 99.99 -99.99  34.09 
1972 10 99.99 -99.99  30.00 
1972 11 99.99 -99.99  21.30 
1972 12 99.99 -99.99  21.30 
1973 01 99.99 -99.99  20.60 
1973 02 99.99 -99.99  23.70 
1973 03 99.99 -99.99  24.90 
1973 04 99.99 -99.99  23.90 
1973 05 99.99 -99.99  32.40 
1973 07 99.99 -99.99  33.09 
1973 08 99.99 -99.99  30.70 
1973 09 99.99 -99.99  32.90 
1973 10 99.99 -99.99  29.60 
1973 12 99.99 -99.99  21.70 
1974 01 99.99 -99.99  18.40 
1974 02 99.99 -99.99  22.10 
1974 03 99.99 -99.99  26.20 
1974 04 99.99 -99.99  31.40 
1974 05 99.99 -99.99  32.40 
1974 06 99.99 -99.99  33.80 
1974 07 99.99 -99.99  32.80 
1974 08 99.99 -99.99  33.20 
1974 09 99.99 -99.99  32.70 
1974 10 99.99 -99.99  30.00 
1974 11 99.99 -99.99  24.20 
1974 12 99.99 -99.99  18.70 
1975 01 99.99 -99.99  17.29 
1975 02 99.99 -99.99  23.20 
1975 03 99.99 -99.99  26.40 
1975 04 99.99 -99.99  31.40 
1975 05 99.99 -99.99  34.20 
1975 06 99.99 -99.99  34.09 
1975 07 99.99 -99.99  32.80 
1975 08 99.99 -99.99  33.20 
1975 09 99.99 -99.99  32.20 
1975 10 99.99 -99.99  28.70 
1975 11 99.99 -99.99  25.30 
1975 12 99.99 -99.99  20.00 
1976 01 99.99 -99.99  15.80 
1976 02 99.99 -99.99  23.40 
1976 03 99.99 -99.99  26.50 
1976 04 39.84 -99.99  30.70 
1976 05 99.99 -99.99  34.50 
1976 06 99.99 -99.99  34.70 
1976 07 99.99 -99.99  33.50 
1976 08 99.99 -99.99  33.70 
1976 09 99.99 -99.99  32.90 
1976 10 99.99 -99.99  31.60 
1976 11 99.99 -99.99  25.20 
1976 12 99.99 -99.99  22.00 
1977 01 99.99 -99.99  20.10 
1977 02 99.99 -99.99  22.10 
1977 03 99.99 -99.99  23.10 
1977 05 99.99 -99.99  33.09 
1977 06 99.99 -99.99  34.00 
1977 07 99.99 -99.99  33.40 
1977 08 99.99 -99.99  32.80 
1977 09 99.99 -99.99  33.20 
1977 10 99.99 -99.99  28.70 
