1981 05 99.99 -99.99  28.00 
1981 08 99.99 -99.99  28.60 
1981 10 99.99 -99.99  29.50 
1981 12 99.99 -99.99  27.90 
1982 02 99.99 -99.99  27.50 
1982 07 99.99 -99.99  26.50 
1982 08 99.99 -99.99  26.60 
1982 09 99.99 -99.99  23.10 
1982 12 99.99 -99.99  29.30 
1983 02 99.99 -99.99  28.20 
1983 03 99.99 -99.99  28.90 
1983 04 99.99 -99.99  28.50 
1983 06 99.99 -99.99  27.50 
1983 07 99.99 -99.99  26.70 
1983 09 99.99 -99.99  28.20 
1983 10 99.99 -99.99  29.00 
1983 12 99.99 -99.99  29.40 
1984 02 99.99 -99.99  27.00 
1984 03 99.99 -99.99  27.70 
1984 05 99.99 -99.99  28.10 
1984 06 99.99 -99.99  26.90 
1984 07 99.99 -99.99  27.20 
1984 08 99.99 -99.99  27.90 
1984 09 99.99 -99.99  27.90 
1984 12 99.99 -99.99  27.70 
1987 04 99.99 -99.99  29.10 
1989 07 99.99 -99.99  28.00 
1989 09 99.99 -99.99  28.10 
1990 01 99.99 -99.99  27.30 
