74% (1984)

70% (1980)

58% (1981)

69% (1979)

65% (1983)

60% (1975)

78% (1987)

70% (1981)

67% (1983)

67% (1976)

60% (1982)

80% (1978)

80% (1989)

68% (1987)

50% (1986)