2007

7.3

2005

6.1

2008

6.1

1987

7.7

2011

5.0

1995

5.8

1991

6.8

1984

6.0

1976

7.6

2003

7.8

2006

7.4

2004

7.1

1991

7.0

1929

6.0

1941

5.8

1962

6.5

1950

6.6

1986

6.3

1981

6.5

1996

6.7