72% (1981)

69% (1983)

71% (1982)

72% (1975)

63% (1979)

71% (1973)

73% (1988)

67% (1976)

65% (1976)

61% (1980)

62% (1977)

62% (1985)

60% (1984)

67% (1988)

60% (1987)

62% (1974)

57% (1990)

52% (1972)

33% (1981)

0% (1990)