61% (2009)

61% (2013)

71% (1981)

71% (1986)

63% (1980)

71% (1999)

65% (1995)

70% (1984)

72% (1992)

66% (2002)

67% (1996)

68% (2003)

56% (1987)

71% (1990)

55% (1991)

63% (1997)

62% (1999)

73% (1989)

60% (1980)

60% (2004)