g ;YEARNMONTHNH2OCONTN  1947 4 26.20 1949 4 49.20 1950 4 28.10 1951 4 29.90 1952 4 58.40 1953 4 43.90 1954 4 48.70 1955 4 27.50 1956 4 50.70 1957 4 29.50 1958 4 84.60 1959 4 39.40 1960 4 39.70 1961 4 37.20 1962 4 45.50 1963 4 10.00 1964 4 22.10 1965 4 21.30 1966 4 46.70 1967 4 40.20 1968 4 29.50 1969 4 61.50 1970 4 20.70 1971 4 36.50 1972 4 21.70 1973 4 58.50 1974 4 38.30 1975 4 58.20 1976 4 21.90 1977 4 14.60 1978 4 58.80 1979 4 29.60 1980 4 33.90 1981 4 30.00 1983 4 83.00 1984 4 39.00 1985 4 36.50 1986 4 46.10 1987 4 30.50 1988 4 19.50 1989 4 27.80 1990 4 12.20 1991 4 28.00 1992 4 46.60 1993 4 49.00 1994 4 25.30 1995 4 59.20 1996 4 29.70 1997 4 17.80 1998 4 80.00 1999 4 49.00* 2000 4 50.20* 2001 4 34.60* 2002 4 37.30* 2003 4 39.50 2000 4 50.20 2001 4 34.60 2002 4 37.30 2003 4 39.50