81% (1959)

63% (1967)

74% (1968)

73% (1980)

76% (1962)

78% (1973)

69% (1975)

72% (1977)

71% (1981)

72% (1970)

78% (1969)

72% (1968)

70% (1979)

73% (1962)

63% (1972)

72% (1964)

71% (1970)

67% (1969)

70% (1971)

57% (1964)