73% (1976)

69% (1970)

65% (1975)

62% (1973)

76% (1972)

58% (1983)

66% (1977)

66% (1974)

57% (1977)

62% (1980)

58% (1976)

60% (1981)

71% (1973)

54% (1979)

55% (1985)

62% (1977)

58% (1977)

64% (1975)

64% (1984)

44% (1986)