51% (1977)

49% (1978)

63% (1964)

51% (1972)

55% (1980)

51% (1988)

45% (1973)

45% (1989)

64% (1965)

51% (1975)

49% (1990)

45% (1981)

55% (1969)

54% (1967)

62% (1972)

48% (1976)

56% (1980)

59% (1964)

58% (1979)

36% (1988)