1989

6.3

1974

7.0

2007

6.6

1991

7.1

1999

6.7

2005

5.8

2001

5.8

2006

4.9

2008

5.8

1998

6.5

2007

6.5

2016

6.4

2003

5.9

1980

6.3

1955

6.2

1977

6.1

1995

6.2

1947

7.4

1999

6.5

2000

5.2