1976

4.7

1983

2.9

2009

7.2

2007

6.6

1980

6.1

1983

5.0

1993

7.3

1947

7.0

2009

6.7

2002

5.5

1974

5.8

1975

6.8

1998

5.0

1991

5.1

1993

6.2

2002

6.1

1984

4.8

1982

7.8

2005

7.7

1991

8.3