1981

8.6

2017

8.3

1999

7.9

2018

6.8

1967

7.4

1974

8.1

1998

7.5

2015

7.6

2011

8.5

1998

7.0

2005

7.0

2013

7.2

2011

8.2

2021

8.8

2014

7.8

2008

8.9

2019

8.7

1994

8.4

2016

8.6

2017

8.2