1980

8.3

2005

5.8

1972

7.4

2012

5.5

2005

6.2

1990

5.2

2011

5.1

2013

7.0

2013

5.7

2017

3.9

2001

4.3

1999

6.8

1951

7.1

1987

5.3

2016

6.7

1987

6.0

1997

6.5

2005

5.2

2012

6.1

2014

6.4