1934

4.1

1993

6.3

1990

7.7

1991

6.4

1966

7.1

1999

7.1

2006

5.8

2009

6.6

2002

5.4

1991

6.7

2001

7.3

2002

6.2

1997

6.8

1960

7.2

2005

6.7

1975

6.9

2005

7.3

2002

6.1

2000

7.2

1999

6.6