76% (1967)

66% (1981)

67% (1980)

71% (1981)

69% (1970)

57% (1980)

74% (1968)

61% (1979)

56% (1972)

56% (1980)

61% (1974)

66% (1971)

57% (1981)

62% (1982)

54% (1972)

62% (1974)

58% (1973)

45% (1970)

68% (1975)

60% (1975)