1980 -999 -999 -999 8.6 8.0 7.6 9.2 8.0 6.5 9.0 6.9 8.2 1981 8.1 7.3 8.3 6.4 5.7 5.4 6.0 5.2 6.9 6.4 6.5 8.8 1982 7.5 6.7 6.1 4.9 4.4 5.7 4.9 4.3 5.3 5.9 5.8 8.0 1983 6.0 4.8 5.4 5.6 5.7 5.6 4.4 5.2 5.7 6.2 7.4 5.3 1984 6.1 7.5 7.8 7.9 7.8 8.7 7.1 6.2 6.7 8.5 6.7 8.5 1985 6.8 7.1 6.3 5.8 6.2 5.0 5.3 4.6 6.2 6.1 8.6 6.0 1986 7.6 7.6 6.6 5.0 5.8 4.8 3.6 5.1 4.0 5.9 5.4 6.5 1987 7.4 7.6 6.0 4.4 5.1 5.1 5.9 6.8 5.3 7.8 5.5 5.7 1988 7.3 6.2 5.2 7.0 5.0 6.0 4.9 7.2 6.1 7.0 8.0 8.9 1989 8.4 6.9 7.2 5.5 5.3 5.7 5.1 5.7 5.7 6.1 8.4 7.5 1990 8.1 6.5 -999 -999 -999 -999 -999 -999 -999 -999 -999 -999