77% (1967)

71% (1981)

68% (1980)

66% (1981)

74% (1968)

57% (1980)

69% (1970)

56% (1980)

66% (1971)

76% (1970)

61% (1979)

59% (1970)

59% (1977)

58% (1981)

50% (1969)

64% (1970)

62% (1974)

59% (1973)

63% (1982)

61% (1974)