1982

3.6

2004

8.1

1959

7.8

1970

5.7

2007

8.0

2008

4.9

1954

5.9

2008

5.7

1955

6.0

2009

7.1

1993

7.1

2008

6.7

2014

4.8

1978

7.3

1992

6.8

1996

6.2

1999

6.9

1999

6.5

2000

6.3

2008

6.5