1973 01 99.99 -99.99  21.70 
1973 02 99.99 -99.99  23.40 
1973 03 99.99 -99.99  26.70 
1973 04 99.99 -99.99  26.40 
1973 05 99.99 -99.99  26.80 
1973 06 99.99 -99.99  25.70 
1973 07 99.99 -99.99  25.60 
1973 08 99.99 -99.99  25.10 
1973 09 99.99 -99.99  25.30 
1973 10 99.99 -99.99  24.30 
1973 11 99.99 -99.99  23.40 
1973 12 99.99 -99.99  19.29 
1974 01 99.99 -99.99  21.70 
1974 02 99.99 -99.99  21.20 
1974 03 99.99 -99.99  23.70 
1974 04 99.99 -99.99  25.80 
1974 05 99.99 -99.99  26.60 
1974 06 99.99 -99.99  25.70 
1974 07 99.99 -99.99  24.20 
1974 08 99.99 -99.99  24.40 
1974 09 99.99 -99.99  24.90 
1974 10 99.99 -99.99  23.30 
1974 11 99.99 -99.99  22.80 
1974 12 99.99 -99.99  21.50 
1975 01 99.99 -99.99  22.30 
1975 02 99.99 -99.99  22.50 
1975 03 99.99 -99.99  25.20 
1975 04 99.99 -99.99  27.00 
1975 05 99.99 -99.99  28.60 
1975 06 99.99 -99.99  26.30 
1975 07 99.99 -99.99  25.10 
1975 08 99.99 -99.99  24.30 
1975 09 99.99 -99.99  24.80 
1975 10 99.99 -99.99  24.30 
1975 11 99.99 -99.99  23.10 
1975 12 99.99 -99.99  21.20 
1976 01 99.99 -99.99  20.10 
1976 02 99.99 -99.99  20.40 
1976 03 99.99 -99.99  24.20 
1976 04 99.99 -99.99  25.50 
1976 05 99.99 -99.99  26.20 
1976 06 99.99 -99.99  24.70 
1976 07 99.99 -99.99  24.20 
1976 08 99.99 -99.99  24.40 
1976 09 99.99 -99.99  25.00 
1976 10 99.99 -99.99  25.00 
1976 11 99.99 -99.99  22.90 
1976 12 99.99 -99.99  21.20 
1977 01 99.99 -99.99  21.10 
1977 02 99.99 -99.99  21.80 
1977 03 99.99 -99.99  24.60 
1977 04 99.99 -99.99  24.20 
1977 05 99.99 -99.99  26.60 
1977 06 99.99 -99.99  25.50 
1977 07 99.99 -99.99  24.70 
1977 08 99.99 -99.99  24.90 
1977 09 99.99 -99.99  25.10 
1977 10 99.99 -99.99  24.70 
1977 11 99.99 -99.99  23.70 
1977 12 99.99 -99.99  22.20 
1978 01 99.99 -99.99  21.30 
1978 02 99.99 -99.99  22.00 
1978 03 99.99 -99.99  23.20 
1978 04 99.99 -99.99  26.10 
1978 05 99.99 -99.99  27.90 
1978 06 99.99 -99.99  26.10 
1978 07 99.99 -99.99  25.50 
1978 08 99.99 -99.99  25.00 
1978 09 99.99 -99.99  25.40 
1978 10 99.99 -99.99  23.70 
1978 11 99.99 -99.99  23.60 
1978 12 99.99 -99.99  22.70 
1979 01 99.99 -99.99  21.60 
1979 02 99.99 -99.99  22.90 
1979 03 99.99 -99.99  24.60 
1979 04 99.99 -99.99  27.90 
1979 05 99.99 -99.99  28.10 
1979 06 99.99 -99.99  26.00 
1979 07 99.99 -99.99  26.20 
1979 08 99.99 -99.99  25.60 
1979 09 99.99 -99.99  25.70 
1979 10 99.99 -99.99  25.40 
1979 11 99.99 -99.99  23.40 
1979 12 99.99 -99.99  22.40 
1980 01 99.99 -99.99  23.40 
1980 02 99.99 -99.99  23.60 
1980 03 99.99 -99.99  27.00 
1980 04 99.99 -99.99  26.90 
1980 05 99.99 -99.99  30.00 
1980 06 99.99 -99.99  27.00 
1980 07 99.99 -99.99  26.80 
1980 08 99.99 -99.99  27.20 
1980 09 99.99 -99.99  26.70 
1980 10 99.99 -99.99  25.70 
1980 11 99.99 -99.99  23.90 
1980 12 99.99 -99.99  21.60 
1981 01 99.99 -99.99  21.50 
1981 02 99.99 -99.99  23.00 
1981 03 99.99 -99.99  26.50 
1981 04 99.99 -99.99  27.30 
1981 05 99.99 -99.99  29.90 
1981 06 99.99 -99.99  26.90 
1981 07 99.99 -99.99  26.50 
1981 08 99.99 -99.99  27.10 
1981 09 99.99 -99.99  26.50 
1981 10 99.99 -99.99  26.00 
1981 11 99.99 -99.99  24.00 
1981 12 99.99 -99.99  23.40 
