1988 01 99.99 -99.99  26.20 
1988 02 99.99 -99.99  26.30 
1988 03 99.99 -99.99  26.10 
1988 04 99.99 -99.99  26.50 
1988 05 99.99 -99.99  26.60 
1988 06 99.99 -99.99  26.50 
1988 07 99.99 -99.99  27.10 
1988 08 99.99 -99.99  27.60 
1988 09 99.99 -99.99  32.09 
1988 10 99.99 -99.99  27.00 
1988 11 99.99 -99.99  26.10 
1988 12 99.99 -99.99  26.30 
1989 01 99.99 -99.99  25.30 
1989 02 99.99 -99.99  25.30 
1989 03 99.99 -99.99  25.30 
1989 04 99.99 -99.99  25.90 
1989 05 99.99 -99.99  25.70 
1989 06 99.99 -99.99  26.30 
1989 07 99.99 -99.99  25.80 
1989 08 99.99 -99.99  27.10 
1989 09 99.99 -99.99  28.00 
1989 10 99.99 -99.99  27.30 
1989 11 99.99 -99.99  26.90 
1989 12 99.99 -99.99  26.00 
1990 01 99.99 -99.99  25.80 
1990 02 99.99 -99.99  25.60 
1990 03 99.99 -99.99  26.90 
1990 04 99.99 -99.99  26.70 
1990 05 99.99 -99.99  27.10 
1990 06 99.99 -99.99  29.70 
1990 07 99.99 -99.99  25.30 
1990 08 99.99 -99.99  27.10 
1990 09 99.99 -99.99  27.10 
1990 10 99.99 -99.99  27.70 
1990 11 99.99 -99.99  26.70 
1991 01 99.99 -99.99  25.90 
1991 03 99.99 -99.99  26.00 
1991 04 99.99 -99.99  26.50 
1991 05 99.99 -99.99  26.80 
1991 06 99.99 -99.99  23.30 
1991 07 99.99 -99.99  26.30 
1991 08 99.99 -99.99  27.10 
1991 09 99.99 -99.99  26.60 
1991 10 99.99 -99.99  26.70 
1991 12 99.99 -99.99  26.50 
1992 01 99.99 -99.99  26.70 
1992 02 99.99 -99.99  26.00 
1992 03 99.99 -99.99  25.90 
1992 04 99.99 -99.99  27.50 
1992 05 99.99 -99.99  27.90 
1992 06 99.99 -99.99  27.80 
1992 07 99.99 -99.99  27.60 
1992 08 99.99 -99.99  27.80 
1992 10 99.99 -99.99  27.60 
1992 11 99.99 -99.99  27.50 
1992 12 99.99 -99.99  26.20 
1993 01 99.99 -99.99  25.90 
1993 02 99.99 -99.99  25.60 
1993 03 99.99 -99.99  26.30 
1993 04 99.99 -99.99  26.80 
1993 05 99.99 -99.99  28.00 
1993 06 99.99 -99.99  27.80 
1993 11 99.99 -99.99  27.40 
1993 12 99.99 -99.99  27.60 
1994 02 99.99 -99.99  26.00 
1994 03 99.99 -99.99  26.90 
1994 04 99.99 -99.99  27.40 
1994 05 99.99 -99.99  28.60 
1994 06 99.99 -99.99  26.40 
1994 07 99.99 -99.99  26.70 
1994 08 99.99 -99.99  27.20 
1994 09 99.99 -99.99  29.00 
1995 01 99.99 -99.99  26.20 
1995 02 99.99 -99.99  26.20 
1995 03 99.99 -99.99  26.80 
1995 04 99.99 -99.99  26.20 
1995 05 99.99 -99.99  26.50 
