| YEAR(S) | JAN | FEB | MAR | APR | MAY | JUN | JUL | AUG | SEP | OCT | NOV | DEC | ANN | |||||||||||||
| 1970 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | 1.12 | f | ----- | z | ----- | z | ----- | z |
| 1971 | 0.00 | a | 0.50 | ----- | z | 0.31 | 0.47 | 0.15 | i | 0.73 | w | 0.34 | 0.45 | ----- | z | ----- | z | ----- | z | ----- | z | |||||
| 1972 | ----- | z | 0.00 | 0.00 | d | 0.00 | a | ----- | z | 0.50 | 0.60 | 0.74 | 0.40 | b | 0.00 | l | ----- | z | ----- | z | ----- | z | ||||
| 1973 | ----- | z | 0.00 | ----- | z | 0.25 | 0.25 | 0.30 | ----- | z | 0.65 | 2.00 | 0.10 | d | 0.00 | d | 0.10 | c | ----- | z | ||||||
| 1974 | 0.00 | a | 1.00 | 0.04 | 0.10 | 0.35 | 1.95 | 0.53 | 0.46 | ----- | z | 0.08 | c | 0.30 | 0.08 | ----- | z | |||||||||
| 1975 | 0.34 | 0.15 | 0.10 | 0.10 | ----- | z | 0.40 | 0.31 | 0.47 | 0.50 | 0.16 | 0.13 | 0.20 | ----- | z | |||||||||||
| 1976 | 0.11 | 0.48 | 0.16 | 0.01 | 0.42 | 0.71 | 0.42 | 0.86 | 0.64 | 0.27 | 0.36 | 0.18 | 0.86 | |||||||||||||
| 1977 | 0.14 | 0.23 | 0.17 | ----- | z | 0.60 | 0.35 | 2.06 | 1.09 | 0.41 | a | 0.38 | 0.07 | 0.10 | ----- | z | ||||||||||
| 1978 | 0.19 | 0.13 | 0.27 | 0.12 | 0.00 | 0.64 | 0.21 | 0.53 | 0.92 | 0.43 | 0.23 | 0.19 | 0.92 | |||||||||||||
| 1979 | 0.04 | 0.02 | 0.11 | 0.15 | 0.09 | 0.32 | 0.34 | 0.38 | 0.32 | 0.52 | 0.20 | 0.08 | 0.52 | |||||||||||||
| 1980 | 0.27 | 0.26 | 0.05 | 0.22 | 0.47 | 0.94 | 1.00 | 0.71 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ||||||||
| 1981 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1982 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1983 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1984 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1985 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1986 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1987 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1988 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1989 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1990 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1991 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1992 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1993 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1994 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1995 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1996 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1997 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1998 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1999 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | 0.00 | f | ----- | z | 0.00 | j | ----- | z |
| 2000 | 0.00 | g | 0.00 | e | 0.00 | d | 0.00 | a | 0.00 | ----- | z | ----- | z | ----- | z | 1.20 | b | 0.00 | h | 0.00 | f | 0.00 | f | ----- | z | |
| 2001 | 0.00 | e | 0.00 | f | 0.00 | g | 0.00 | d | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2002 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2003 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2004 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2005 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2006 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2007 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2008 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2009 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2010 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2011 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2012 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2013 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2014 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2015 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2016 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2017 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| Period of Record Statistics | ||||||||||||||||||||||||||
| MEAN | 0.12 | 0.25 | 0.10 | 0.11 | 0.29 | 0.68 | 0.68 | 0.62 | 0.76 | 0.28 | 0.18 | 0.13 | 0.77 | |||||||||||||
| S.D. | 0.13 | 0.31 | 0.09 | 0.11 | 0.22 | 0.52 | 0.61 | 0.23 | 0.55 | 0.17 | 0.13 | 0.05 | 0.22 | |||||||||||||
| SKEW | 0.56 | 1.39 | 0.59 | 0.45 | -0.22 | 1.78 | 1.65 | 0.65 | 1.45 | 0.15 | -0.07 | 0.25 | -0.65 | |||||||||||||
| MAX | 0.34 | 1.00 | 0.27 | 0.31 | 0.60 | 1.95 | 2.06 | 1.09 | 2.00 | 0.52 | 0.36 | 0.20 | 0.92 | |||||||||||||
| MIN | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.30 | 0.21 | 0.34 | 0.32 | 0.08 | 0.00 | 0.08 | 0.52 | |||||||||||||
| YRS | 9 | 11 | 9 | 11 | 9 | 9 | 8 | 10 | 9 | 7 | 7 | 7 | 3 | |||||||||||||