74% (1993)

66% (2009)

63% (2006)

71% (1981)

61% (2003)

59% (2007)

68% (2008)

73% (1975)

66% (1992)

61% (1979)

68% (1977)

65% (1997)

61% (2000)

62% (1982)

67% (1991)

66% (2009)

52% (1994)

62% (1979)

58% (2002)

57% (2005)