2007

6.1

1997

6.4

2002

6.4

2006

7.1

2001

6.0

1992

6.0

1977

6.0

1991

6.5

2005

6.1

1990

6.4

1997

6.2

1994

5.2

1985

6.7

1986

5.6

2003

7.8

1995

6.0

1993

6.5

1998

6.3

2002

5.8

1996

7.1