60% (1997)

63% (1990)

56% (1996)

67% (1992)

63% (1990)

68% (1988)

64% (1991)

55% (1993)

44% (1988)

43% (1995)

40% (1989)

40% (1990)

50% (1996)

43% (1990)

46% (1998)

30% (1992)

25% (1996)

24% (1991)

47% (1995)

55% (1994)