1987

7.1

2009

7.6

1997

7.9

2012

7.2

2014

8.5

1999

8.0

2016

6.5

2012

7.8

2014

7.8

2006

7.4

2005

6.9

2016

7.7

1994

8.5

2015

7.1

1994

8.7

2018

8.0

2017

8.2

2015

7.2

2018

6.5

1977

8.2