58% (1985)

70% (1988)

74% (1989)

56% (1977)

58% (1988)

58% (1983)

48% (1981)

61% (1985)

64% (1977)

65% (1984)

60% (1983)

66% (1991)

71% (1980)

60% (1984)

53% (1982)

50% (1986)

51% (1981)

50% (1975)

59% (1974)

63% (1979)