78% (1967)

71% (1971)

71% (1970)

72% (1970)

68% (1968)

63% (1966)

63% (1969)

61% (1968)

53% (1966)

61% (1976)

57% (1967)

51% (1975)

56% (1965)

48% (1967)

56% (1964)

63% (1965)

58% (1966)

54% (1964)

53% (1967)

53% (1970)