1991

7.4

2014

4.8

2007

6.1

2004

5.2

2017

7.0

2002

6.0

1976

7.6

1969

6.8

1967

6.9

1970

3.8

2005

4.2

1996

8.0

2013

6.2

1952

7.9

1977

0.0

2014

6.0

2015

5.1

1995

7.6

1997

3.5

2010

6.6