74% (1974)

71% (1980)

71% (1976)

70% (1975)

67% (1977)

59% (1980)

64% (1979)

63% (1980)

66% (1974)

47% (1978)

50% (1977)

73% (1978)

44% (1980)

50% (1980)

63% (1975)

66% (1973)

67% (1981)

50% (1977)

68% (1975)

35% (1979)