71% (1976)

72% (1980)

75% (1974)

59% (1980)

64% (1979)

70% (1975)

44% (1980)

67% (1977)

67% (1981)

63% (1980)

66% (1974)

54% (1980)

73% (1978)

63% (1975)

47% (1978)

50% (1977)

50% (1977)

50% (1980)

30% (1976)

35% (1979)