74% (1974)

71% (1980)

71% (1976)

59% (1980)

70% (1975)

67% (1981)

63% (1979)

62% (1980)

66% (1974)

62% (1975)

50% (1980)

67% (1977)

74% (1978)

47% (1978)

44% (1980)

54% (1980)

69% (1975)

48% (1977)

62% (1973)

50% (1977)