71% (1970)

65% (1975)

70% (1967)

72% (1976)

62% (1973)

58% (1972)

61% (1972)

67% (1973)

53% (1971)

57% (1973)

70% (1974)

72% (1971)

55% (1971)

67% (1973)

69% (1971)

75% (1971)

70% (1972)

67% (1975)

58% (1974)

49% (1970)