77% (1967)

71% (1981)

56% (1970)

68% (1980)

69% (1970)

74% (1968)

66% (1971)

71% (1968)

66% (1981)

58% (1980)

75% (1970)

57% (1972)

61% (1974)

59% (1977)

64% (1970)

56% (1980)

58% (1981)

61% (1973)

62% (1974)

59% (1973)