73% (1976)

70% (1970)

76% (1972)

65% (1975)

57% (1977)

64% (1984)

72% (1973)

60% (1981)

66% (1977)

65% (1974)

63% (1975)

62% (1977)

54% (1979)

43% (1986)

59% (1977)

62% (1980)

58% (1976)

62% (1973)

58% (1983)

55% (1985)