60% (1973)

57% (1976)

50% (1975)

38% (1979)

45% (1985)

42% (1973)

52% (1977)

39% (1987)

49% (1971)

38% (1972)

42% (1986)

47% (1971)

44% (1988)

70% (1977)

46% (1972)

55% (1983)

57% (1976)

25% (1981)

47% (1978)

48% (1977)