68% (1967)

64% (1963)

54% (1971)

64% (1965)

50% (1975)

59% (1967)

49% (1974)

50% (1973)

61% (1973)

53% (1975)

57% (1971)

63% (1972)

61% (1970)

72% (1974)

61% (1963)

63% (1967)

55% (1974)

53% (1973)

52% (1975)

50% (1963)