1971    -999    -999   -11.2   -14.7   -16.9   -16.0   -20.6   -20.0   -20.8   -16.2   -11.9    -5.2 
1972    -2.6    -6.3   -11.1   -13.5   -19.1   -18.3   -18.8   -21.3   -19.9   -19.5   -12.4    -5.1 
1973    -4.1    -9.0   -12.0   -15.5   -17.7   -19.3   -19.7   -21.3   -21.3   -18.8   -9.3     -5.6 
1974    -4.0    -8.1   -11.6   -17.5   -18.6   -16.0   -24.3   -20.6   -20.1   -18.2   -10.2    -4.5 
1975    -3.9    -7.1   -11.2   -16.8   -19.2   -21.6   -18.9   -24.4   -22.7   -19.7   -11.2    -5.5 
1976    -3.8    -6.6   -12.5   -20.9   -20.3   -23.4   -22.0   -21.3   -23.1   -22.9   -10.2    -3.1 
1977    -2.7    -7.1   -11.7   -15.5   -20.7   -20.6   -23.2   -20.1   -23.4   -17.2   -10.8    -5.2 
1978    -5.4    -6.2   -9.5    -14.0   -20.1   -22.3   -17.8   -25.5   -22.3   -18.1   -10.7    -6.3 
1979    -4.9    -7.2   -9.9    -13.5   -19.2   -19.7   -24.7   -20.9   -19.2   -17.4   -9.8     -3.0 
1980    -3.6    -6.2   -8.2    -13.0   -15.6   -21.9   -20.5   -20.8   -17.7   -20.0   -9.4     -5.0 
1981    -5.2    -5.8   -10.1   -13.7   -17.5   -16.6   -19.3   -18.5   -18.8   -16.3   -12.0    -5.6 
1982    -4.3    -6.0   -12.5   -18.1   -16.9   -16.7   -21.7   -23.0   -21.2   -17.3   -9.8     -3.7 
1983    -3.6    -5.0   -10.2   -14.8   -15.4   -20.1   -24.4   -24.5   -17.7   -18.1   -11.8    -4.7 
1984    -4.1    -7.6   -10.9   -17.0   -16.9   -23.8   -25.8   -20.2   -19.5   -15.2   -11.9    -5.0 
1985    -3.9    -7.0   -10.9   -15.6   -19.4   -20.6   -23.1   -22.5   -22.8   -19.3   -11.4    -5.9 
1986    -4.3    -6.5   -8.8    -14.1   -16.9   -17.6   -20.4   -21.2   -22.8   -17.1   -11.2    -5.9 
1987    -4.0    -6.3   -8.9    -14.6   -19.8   -16.6   -18.6   -21.6   -20.6   -15.3   -11.3    -6.2 
1988    -4.7    -6.7   -11.4   -14.8   -20.1   -20.3   -22.3   -21.9   -17.4   -15.5   -10.7    -5.0 
1989    -5.2    -8.1   -10.9   -15.6   -21.3   -25.1   -20.5   -24.1   -18.4   -16.9   -10.9    -4.7 
1990    -4.1    -7.5   -11.5   -17.8   -16.9   -22.0   -15.9   -23.0   -23.5   -17.4   -10.2    -4.6 
1991    -4.3    -6.5    -999    -999    -999    -999    -999    -999    -999    -999    -999    -999
2008    -999    -999    -999   -18.4   -22.1   -21.7   -21.3   -19.3   -19.4    -999    -999    -999