1950

7.7

1990

7.3

1980

6.3

1987

6.4

2008

7.0

2001

6.8

2006

4.2

2005

6.2

1923

0.0

1954

3.0

1999

7.1

1996

6.4

1923

7.5

2007

5.8

1992

6.7

1993

6.6

1970

7.6

1988

7.3

1998

6.1

1987

6.6