2008

6.5

1998

6.2

1997

5.7

1986

7.0

2002

6.2

1999

5.5

1996

7.2

2002

6.7

1998

7.1

1980

6.7

2004

5.9

1999

6.7

2009

6.2

2009

4.5

1995

7.3

2000

6.1

2001

6.2

1988

5.9

2007

6.1

1937

6.7