1934

4.1

1962

6.0

1990

7.7

1966

7.1

1999

7.1

2006

5.8

2001

7.3

2002

6.2

1997

6.8

1960

7.2

1975

6.9

1998

7.2

2000

6.5

1958

6.6

2004

6.1

2007

7.5

1979

8.1

2003

5.8

2002

6.3

2006

8.2