73% (1976)

69% (1970)

71% (1973)

62% (1973)

66% (1977)

65% (1975)

76% (1972)

57% (1977)

65% (1974)

62% (1980)

58% (1977)

55% (1985)

59% (1981)

64% (1975)

62% (1977)

64% (1984)

58% (1983)

57% (1976)

65% (1978)

44% (1986)