55% (1973)

44% (1974)

53% (1973)

45% (1961)

46% (1986)

59% (1980)

55% (1984)

57% (1961)

46% (1980)

53% (1980)

34% (1969)

58% (1987)

50% (1976)

46% (1980)

48% (1985)

44% (1988)

48% (1976)

45% (1971)

53% (1976)

50% (1983)