| 1984 | 1985 | 1986 | 1987 | 1988 | 1989 | 1990 | 1991 | 1992 | 1993 | 1994 | 1995 | 1996 | 1997 | 1998 | 1999 | 2000 | 2001 | Ave. | |
| Jan | 18.95 | 21.1 | 17.4 | 11.55 | 24.05 | 9.0 | 7.1 | 8.49 | 16.31 | 10.2 | 4.15 | 4.0 | 7.2 | 5.6 | 11.8 | 12.4 | 16.3 | 12.09 | |
| Feb | 14.15 | 7.25 | 12.15 | ND | 0.25 | 10.8 | 16.87 | 9.86 | 15.4 | 5.5 | 7.35 | 7.85 | 10.31 | 4.85 | 13.05 | 6.65 | 5.55 | 9.63 | |
| Mar | 9.3 | 13.75 | 5.0 | ND | 4.7 | 10.5 | 8.15 | 6.84 | 13.08 | 10.50 | 10.10 | 6.75 | 12.45 | 11.05 | 9.0 | 16.75 | 12.45 | 9.64 | |
| Apr | 14.0 | 6.8 | 13.85 | ND | 1.9 | 5.45 | 8.55 | 11.01 | 5.92 | 7.25 | 7.20 | 4.81 | 11.10 | 9.3 | 10.15 | 4.8 | 5.05 | 7.95 | |
| May | 6.0 | 5.55 | 10.8 | 4.5 | 3.1 | 1.55 | 7.2 | 9.2 | 5.1 | 7.87 | 2.85 | 1.55 | 1.69 | 3.35 | 12.7 | 3.8 | 8.75 | 5.62 | |
| June | 3.95 | 2.45 | 7.6 | 3.1 | 1.1 | 1.9 | 2.9 | 2.7 | 1.8 | 3.45 | 3.2 | 6.45 | 3.25 | 2.70 | 3.8 | 2.8 | 3.8 | 3.35 | |
| July | 2.2 | 2.4 | 1.05 | 5.95 | 0.8 | 1.95 | 5.7 | 3.02 | 1.42 | 3.85 | 3.6 | 3.5 | 4.3 | 4.10 | 2.2 | 3.3 | 2.25 | 3.03 | |
| Aug | 4.6 | 3.05 | 3.65 | 5.2 | 2.35 | 3.85 | 8.3 | 4.4 | 1.77 | 4.39 | 4.85 | 4.65 | 4.1 | 10.01 | 7.65 | 8.45 | 7 | 5.19 | |
| Sept | 7.45 | 5.6 | 19.1 | 6.75 | 7.5 | 7.4 | 7.95 | 12.54 | 5.3 | 17.1 | 4.25 | 11.6 | 11.65 | 6.10 | 8.75 | 9.15 | 10.7 | 9.35 | |
| Oct | 11.95 | 13.55 | 23.65 | 12.75 | 13.0 | 12.4 | 8.6 | 12.12 | 12.25 | 14.75 | 16.7 | 11.15 | 12.2 | 14.15 | 13.40 | 24.1 | 10.8 | 12.1 | 13.87 |
| Nov | 11.0 | 7.15 | 13.7 | 22.4 | 24.7 | 17.65 | 14.0 | 22.6 | 14.99 | 17.44 | 16.9 | 12.5 | 6.95 | 10.3 | 7.40 | 20.95 | 13.2 | 9.05 | 14.60 |
| Dec | 10.1 | 6.35 | 13.0 | 18.75 | 9.55 | 16.25 | 17.25 | 3.6 | 10.88 | 17.67 | 10.9 | 11.05 | 9.8 | 21.25 | 16.75 | 11.15 | 7.45 | 7 | 12.15 |
| Total | 109.55 | 107.7 | 118.3 | 144.5 | 111.53 | 92.05 | 84.3 | 111.0 | 106.2 | 116.0 | 115.0 | 82.25 | 80.11 | 111.8 | 94.61 | 135.3 | 99.55 | 100 | 106.45 |