79% (1978)

78% (1976)

82% (1976)

78% (1977)

80% (1975)

79% (1977)

79% (1975)

81% (1976)

81% (1974)

82% (1978)

75% (1974)

71% (1980)

77% (1975)

83% (1973)

67% (1979)

73% (1989)

75% (1974)

70% (1974)

76% (1983)

52% (2000)