58% (1978)

70% (1977)

59% (1980)

51% (1979)

52% (1975)

71% (1972)

63% (1980)

54% (1988)

63% (1988)

60% (1995)

55% (1982)

47% (1995)

57% (1983)

46% (1975)

61% (1999)

65% (1986)

55% (1996)

62% (1980)

54% (1985)

49% (1986)