64% (1975)

62% (1983)

73% (1987)

62% (1980)

60% (1988)

37% (1976)

65% (1984)

75% (1980)

80% (1981)

70% (1982)

68% (1981)

65% (1976)

70% (1984)

67% (1989)

67% (1983)

58% (1973)

70% (1987)

57% (1981)

63% (1974)

70% (1977)