79% (1987)

77% (1997)

79% (1997)

76% (1992)

80% (1990)

74% (1974)

71% (1984)

72% (1976)

76% (1991)

74% (1989)

68% (1996)

65% (1979)

65% (1970)

55% (1995)

61% (1972)

57% (1975)

58% (1982)

62% (1973)

50% (1983)

60% (1972)