60% (1974)

56% (1975)

45% (1977)

74% (1979)

74% (1982)

63% (1975)

66% (1978)

68% (1979)

65% (1975)

75% (1985)

53% (1980)

53% (1981)

67% (1992)

55% (1975)

59% (1981)

65% (1984)

63% (1977)

72% (1996)

55% (1984)

20% (2002)