71% (1970)

65% (1975)

72% (1976)

70% (1967)

53% (1971)

62% (1973)

61% (1972)

67% (1973)

72% (1971)

58% (1972)

70% (1972)

36% (1976)

67% (1973)

58% (1974)

57% (1973)

49% (1970)

70% (1974)

58% (1977)

75% (1971)

69% (1971)