1973 04 99.99 -99.99  13.60 
1973 05 99.99 -99.99  14.40 
1973 06 99.99 -99.99  14.10 
1973 07 99.99 -99.99  13.50 
1973 08 99.99 -99.99  13.60 
1973 09 99.99 -99.99  13.70 
1973 10 99.99 -99.99  12.40 
1973 11 99.99 -99.99  10.00 
1973 12 99.99 -99.99  10.00 
1974 01 99.99 -99.99   9.39 
1974 02 99.99 -99.99   9.80 
1974 03 99.99 -99.99  11.30 
1974 04 99.99 -99.99  13.10 
1974 05 99.99 -99.99  14.10 
1974 06 99.99 -99.99  13.90 
1974 07 99.99 -99.99  12.40 
1974 08 99.99 -99.99  12.90 
1974 09 99.99 -99.99  12.80 
1974 10 99.99 -99.99  11.00 
1974 11 99.99 -99.99   9.50 
1974 12 99.99 -99.99   9.30 
1975 01 99.99 -99.99   8.30 
1975 02 99.99 -99.99   9.89 
1975 03 99.99 -99.99  12.10 
1975 04 99.99 -99.99  14.60 
1975 05 99.99 -99.99  13.90 
1975 06 99.99 -99.99  13.60 
1975 07 99.99 -99.99  12.50 
1975 08 99.99 -99.99  12.70 
1975 09 99.99 -99.99  11.90 
1975 10 99.99 -99.99  10.80 
1975 11 99.99 -99.99   9.70 
1975 12 99.99 -99.99  10.50 
1976 01 99.99 -99.99   9.60 
1976 02 99.99 -99.99  10.80 
1976 03 99.99 -99.99  11.60 
1976 04 99.99 -99.99  12.50 
1976 05 99.99 -99.99  13.60 
1976 06 99.99 -99.99  13.70 
1976 07 99.99 -99.99  13.40 
1976 08 99.99 -99.99  12.90 
1976 09 99.99 -99.99  13.40 
1976 10 99.99 -99.99  12.10 
1976 11 99.99 -99.99  10.00 
1976 12 99.99 -99.99   9.50 
1977 01 99.99 -99.99  11.90 
1977 02 99.99 -99.99  11.40 
1977 03 99.99 -99.99  12.40 
1977 04 99.99 -99.99  11.60 
1977 05 99.99 -99.99  13.80 
1977 06 99.99 -99.99  13.50 
1977 07 99.99 -99.99  12.60 
1977 08 99.99 -99.99  13.30 
1977 09 99.99 -99.99  13.30 
1977 10 99.99 -99.99  12.10 
1977 11 99.99 -99.99  10.10 
1977 12 99.99 -99.99   9.10 
1978 01 99.99 -99.99   9.00 
1978 02 99.99 -99.99  10.10 
1978 03 99.99 -99.99  11.70 
1978 04 99.99 -99.99  14.20 
1978 05 99.99 -99.99  15.10 
1978 06 99.99 -99.99  14.90 
1978 07 99.99 -99.99  13.90 
1978 08 99.99 -99.99  13.80 
1978 09 99.99 -99.99  13.50 
1978 10 99.99 -99.99  12.90 
1978 11 99.99 -99.99  11.20 
1978 12 99.99 -99.99   9.80 
1979 01 99.99 -99.99  10.90 
1979 02 99.99 -99.99  10.30 
1979 03 99.99 -99.99  11.70 
1979 04 99.99 -99.99  13.70 
1979 05 99.99 -99.99  14.50 
1979 06 99.99 -99.99  14.40 
1979 07 99.99 -99.99  14.20 
1979 08 99.99 -99.99  13.60 
1979 09 99.99 -99.99  13.20 
1979 10 99.99 -99.99  12.00 
1979 11 99.99 -99.99  10.80 
1979 12 99.99 -99.99   9.80 
1980 01 99.99 -99.99   9.50 
1980 02 99.99 -99.99  10.10 
1980 03 99.99 -99.99  12.90 
1980 04 99.99 -99.99  13.50 
1980 05 99.99 -99.99  15.00 
1980 06 99.99 -99.99  14.60 
1980 07 99.99 -99.99  14.30 
1980 08 99.99 -99.99  14.60 
1980 09 99.99 -99.99  14.40 
1980 10 99.99 -99.99  13.30 
1980 11 99.99 -99.99  10.00 
1980 12 99.99 -99.99  11.90 
