1980 7.2

1980 7.7

1980 6.9

1980 7.0

1980 6.3

1979 8.3

1978 6.2

1978 8.0

1977 6.9

1977 7.2

1976 6.0

1975 8.1

1973 7.6

1970 3.4

1969 6.8

1968 7.4

1968 6.8

1967 6.7

1967 7.1

1965 6.8