63% (1971)

62% (1974)

59% (1981)

53% (1974)

64% (1969)

60% (1967)

54% (1977)

59% (1965)

50% (1976)

57% (1970)

62% (1966)

68% (1972)

60% (1972)

59% (1973)

69% (1971)

54% (1970)

65% (1974)

55% (1971)

57% (1965)

64% (1965)