76% (1967)

71% (1981)

66% (1981)

67% (1980)

74% (1968)

58% (1980)

69% (1970)

56% (1972)

57% (1980)

66% (1971)

62% (1974)

57% (1970)

61% (1979)

59% (1977)

45% (1970)

62% (1974)

58% (1981)

63% (1982)

57% (1975)

58% (1973)