1934

4.1

2005

6.8

1990

7.7

1999

5.4

1966

7.1

1999

7.1

2006

5.8

2006

7.0

2001

7.3

1984

6.0

2002

6.2

1997

7.5

1978

5.9

1960

7.2

1975

6.9

1944

7.2

2006

5.4

1950

6.8

1956

6.5

2007

6.4