69% (1979)

74% (1984)

60% (1975)

70% (1980)

58% (1981)

67% (1983)

67% (1976)

78% (1987)

68% (1987)

65% (1983)

80% (1978)

70% (1981)

60% (1982)

80% (1989)

50% (1986)