1971

4.5

2005

6.8

2008

5.1

2008

6.5

2006

5.8

1987

5.8

2014

6.2

2013

7.5

1970

6.2

1969

6.4

1960

5.2

1970

5.5

1983

7.6

2014

7.4

1995

6.3

1919

0.0

2009

5.9

2008

6.2

1981

7.0

1965

3.5