73% (1988)

69% (1987)

63% (1986)

65% (1988)

65% (1990)

60% (1978)

66% (1988)

62% (1985)

62% (1975)

62% (1984)

63% (1987)

60% (1985)

63% (1989)

56% (1984)

56% (1971)

62% (1985)

54% (1974)

54% (1980)

53% (1981)

61% (1977)