1988

6.8

2017

7.7

2017

7.7

2014

7.1

2002

5.2

1968

7.5

1980

6.0

2007

5.2

1974

7.2

2008

4.1

2015

7.0

2014

6.5

2000

7.2

2017

4.8

2000

6.7

2004

6.3

1987

7.3

2017

6.9

2016

7.0

2016

6.4