67% (1981)

70% (1980)

63% (1973)

67% (1988)

60% (1980)

55% (1986)

70% (1986)

70% (1983)

52% (1989)

60% (1979)

60% (1977)

60% (1976)

67% (1974)

72% (1976)

77% (1982)

60% (1974)

67% (1977)

53% (1982)

67% (1986)

48% (1988)