58% (1980)

51% (1983)

54% (1985)

43% (1974)

40% (1980)

53% (1979)

47% (1960)

45% (1969)

49% (1985)

46% (1988)

56% (1987)

39% (1985)

49% (1982)

46% (1962)

53% (1980)

41% (1976)

33% (1978)

48% (1976)

46% (1977)

50% (1976)