1975

7.4

1987

5.3

2015

7.6

2017

7.3

1968

8.1

2016

8.2

2014

8.5

2016

6.3

1989

8.3

1997

7.9

1994

8.5

2014

6.1

2010

8.2

2016

6.7

2018

7.4

2019

7.8

2015

7.6

2016

7.0

2015

7.8

2016

7.9