1957 01 99.99 -99.99  24.10 
1957 02 99.99 -99.99  25.20 
1957 03 99.99 -99.99  24.50 
1957 04 99.99 -99.99  24.70 
1957 05 99.99 -99.99  24.80 
1957 06 99.99 -99.99  23.50 
1957 07 99.99 -99.99  23.50 
1957 08 99.99 -99.99  23.60 
1957 09 99.99 -99.99  23.60 
1957 10 99.99 -99.99  23.70 
1957 11 99.99 -99.99  24.20 
1957 12 99.99 -99.99  24.60 
1958 01 99.99 -99.99  24.70 
1958 02 99.99 -99.99  24.80 
1958 03 99.99 -99.99  25.50 
1958 04 99.99 -99.99  25.00 
1958 05 99.99 -99.99  24.90 
1958 06 99.99 -99.99  23.60 
1958 07 99.99 -99.99  22.40 
1958 08 99.99 -99.99  23.00 
1958 09 99.99 -99.99  23.80 
1958 10 99.99 -99.99  23.80 
1958 11 99.99 -99.99  24.00 
1958 12 99.99 -99.99  24.20 
1959 01 99.99 -99.99  23.90 
1959 02 99.99 -99.99  25.30 
1959 03 99.99 -99.99  25.70 
1959 04 99.99 -99.99  24.70 
1959 05 99.99 -99.99  24.80 
1959 06 99.99 -99.99  24.40 
1959 07 99.99 -99.99  23.00 
1959 08 99.99 -99.99  23.00 
1959 09 99.99 -99.99  23.40 
1959 10 99.99 -99.99  23.90 
1959 11 99.99 -99.99  24.00 
1959 12 99.99 -99.99  24.50 
1960 01 99.99 -99.99  24.50 
1960 02 99.99 -99.99  24.90 
1960 03 99.99 -99.99  25.10 
1960 04 99.99 -99.99  24.40 
1960 05 99.99 -99.99  24.50 
1960 06 99.99 -99.99  24.10 
1960 07 99.99 -99.99  23.20 
1960 08 99.99 -99.99  23.70 
1960 09 99.99 -99.99  23.60 
1960 10 99.99 -99.99  23.70 
1960 11 99.99 -99.99  24.30 
1960 12 99.99 -99.99  24.10 
