70% (1977)

66% (1970)

71% (1969)

64% (1973)

59% (1972)

61% (1968)

53% (1971)

50% (1976)

58% (1975)

55% (1969)

67% (1969)

61% (1968)

48% (1970)

58% (1969)

65% (1970)

50% (1969)

55% (1972)

50% (1973)

62% (1978)

49% (1975)