52% (1971)

64% (1975)

71% (1971)

71% (1970)

73% (1976)

57% (1973)

70% (1974)

66% (1975)

66% (1973)

75% (1971)

70% (1967)

69% (1971)

72% (1972)

69% (1976)

62% (1973)

66% (1973)

69% (1974)

65% (1977)

58% (1976)

58% (1974)