60% (1976)

70% (1979)

62% (1991)

62% (1988)

68% (1986)

69% (1971)

61% (2000)

71% (1981)

58% (1993)

71% (1992)

60% (1985)

60% (1988)

72% (1978)

70% (1979)

57% (1993)

67% (1972)

65% (1974)

68% (1983)

61% (1986)

61% (2001)