73% (1976)

66% (1975)

58% (1972)

58% (1976)

69% (1971)

65% (1975)

58% (1974)

70% (1967)

57% (1973)

72% (1971)

59% (1975)

54% (1970)

54% (1970)

67% (1973)

71% (1970)

48% (1973)

53% (1971)

71% (1974)

62% (1972)

56% (1973)