74% (1992)

54% (1983)

69% (1986)

57% (1980)

31% (1997)

73% (1989)

54% (1977)

72% (1993)

55% (1987)

57% (1996)

52% (1984)

38% (1991)

58% (1992)

58% (1993)

52% (1997)

54% (1991)

27% (1996)

42% (1980)

50% (1988)

47% (1982)