1970

7.3

2016

7.9

2005

6.6

1965

7.1

2004

6.2

2013

5.1

2000

7.0

2010

5.2

1991

6.8

2007

7.3

1921

8.2

2011

6.4

1993

5.8

2002

6.4

1995

5.9

1975

7.3

2010

6.1

1950

7.0

1982

5.4

1999

6.1