52% (1973)

43% (1969)

47% (1971)

39% (1970)

20% (1975)

37% (1970)

40% (1969)

35% (1973)

41% (1970)

26% (1968)

20% (1970)

30% (1972)

20% (1974)

45% (1975)

10% (1971)