60% (1975)

46% (1974)

48% (1977)

52% (1976)

65% (1979)

60% (1981)

42% (1978)

47% (1976)

70% (1978)

71% (1975)

31% (1976)

61% (1981)

60% (1983)

51% (1983)

51% (1976)

58% (1975)

49% (1975)

48% (1983)

61% (1974)

50% (1978)