69% (1981)

72% (1988)

58% (1980)

67% (1980)

64% (1977)

61% (1973)

59% (1986)

59% (1986)

61% (1978)

62% (1974)

64% (1974)

68% (1976)

56% (1979)

48% (1979)

72% (1981)

64% (1980)

65% (1986)

52% (1989)

33% (1975)

79% (1981)