69% (1970)

61% (2003)

60% (2002)

64% (1989)

58% (2002)

61% (1994)

70% (1992)

62% (1977)

56% (1986)

60% (2006)

64% (1977)

60% (1978)

56% (2008)

70% (1988)

60% (2009)

58% (1962)

61% (1982)

67% (1997)

55% (1984)

77% (1991)