d 1YEARN MONTHN H2OCONTN  1951 4 31.6 1952 4 80.6 1953 4 46.7 1954 4 35.6 1955 4 22.2 1956 4 61.1 1957 4 27.6 1958 4 50.9 1959 4 24.5 1960 4 25.8 1961 4 38.0 1962 4 31.4 1963 4 9.9 1964 4 36.0 1965 4 22.1 1966 4 41.0 1967 4 35.1 1968 4 22.6 1969 4 64.0 1970 4 24.2 1971 4 50.9 1972 4 26.5 1973 4 27.6 1974 4 41.1 1975 4 66.6 1976 4 28.5 1977 4 12.4 1978 4 15.8 1979 4 16.7 1980 4 20.0 1981 4 4.5 1982 4 20.9 1983 4 46.1 1984 4 27.0 1985 4 36.9 1986 4 17.5 1987 4 26.6 1988 4 5.6 1989 4 33.9 1990 4 9.6 1991 4 9.8 1992 4 13.7 1993 4 31.1 1994 4 11.4 1995 4 26.1 1996 4 25.0 1997 4 8.9 1998 4 43.1 1999 4 36.0