51% (1983)

48% (1979)

63% (1977)

70% (1978)

52% (1976)

57% (1976)

61% (1974)

58% (1975)

61% (1981)

59% (1978)

50% (1975)

65% (1979)

70% (1981)

47% (1976)

48% (1977)

60% (1976)

60% (1981)

52% (1982)

52% (1982)

42% (1978)