1995

5.9

1990

6.1

2000

6.3

2007

6.5

2006

6.5

2003

6.3

2005

6.1

2010

6.1

1999

6.0

1999

5.1

2003

5.7

2007

7.2

2002

6.0

1977

6.5

2006

6.0

1998

5.5

2002

6.1

1994

6.2

2004

5.9

1940

7.1