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| Year | Arctic | Atlantic | Indian | Pacific | 1979 | 3.5 | 1980 | 6.2 | 1981 | 2.0 | 1982 | 2.8 | 1983 | 3.1 | 1984 | 2.5 | 1985 | 0.2 | 2.7 | 1986 | 0.7 | 6.1 | 1987 | 0.1 | 13.2 | 1988 | 0.1 | 24.5 | 1989 | 1.8 | 27.8 |
| Year | Arctic | Atlantic | Indian | Pacific | 1990 | 4.7 | 0.9 | 31.2 | 1991 | 2.0 | 5.4 | 0.8 | 36.6 | 1992 | 6.3 | 9.9 | 1.3 | 49.4 | 1993 | 7.4 | 19.4 | 1.0 | 54.1 | 1994 | 3.7 | 19.4 | 2.0 | 50.6 | 1995 | 3.7 | 22.4 | 14.0 | 53.3 | 1996 | 5.7 | 27.2 | 16.4 | 62.8 | 1997 | 7.3 | 30.8 | 16.4 | 44.1 | 1998 | 4.0 | 33.0 | 10.9 | 40.2 | 1999 | 3.7 | 40.6 | 14.7 | 54.0 | 2000 | 2.3 | 38.2 | 16.9 | 54.9 |