71% (1980)

75% (1974)

71% (1976)

64% (1979)

59% (1980)

67% (1981)

44% (1980)

67% (1974)

67% (1977)

54% (1980)

62% (1975)

74% (1978)

62% (1980)

50% (1980)

47% (1978)

62% (1973)

50% (1977)

45% (1977)

35% (1979)

68% (1975)