74% (1977)

72% (1974)

80% (1978)

72% (1978)

63% (1978)

70% (1983)

71% (1977)

69% (1982)

68% (1984)

56% (1971)

60% (1977)

67% (1983)

71% (1978)

62% (1980)

59% (1980)

55% (1980)

63% (1982)

67% (1970)

69% (1982)

59% (1980)