81% (1959)

74% (1968)

69% (1975)

76% (1962)

78% (1973)

78% (1969)

73% (1980)

72% (1970)

71% (1981)

67% (1969)

63% (1967)

71% (1970)

72% (1964)

72% (1962)

63% (1972)

71% (1979)

72% (1968)

72% (1977)

70% (1971)

65% (1961)