75% (1974)

71% (1980)

64% (1979)

71% (1976)

59% (1980)

67% (1981)

67% (1977)

67% (1974)

62% (1975)

44% (1980)

74% (1978)

47% (1978)

50% (1980)

62% (1980)

45% (1977)

54% (1980)

68% (1975)

30% (1976)

62% (1973)

50% (1977)