59% (1977)

52% (1990)

46% (1983)

50% (1974)

44% (1971)

74% (1984)

54% (1981)

59% (1970)

54% (1976)

58% (1987)

53% (1975)

52% (1973)

42% (1982)

53% (1979)

50% (1986)

50% (1973)

50% (1978)

50% (1988)

49% (1980)