1997

8.4

2004

8.1

2006

7.7

2004

7.1

1975

8.4

1990

7.7

2003

7.5

1994

8.5

2007

7.2

1997

6.5

2020

6.7

2002

6.8

1991

7.4

2007

6.9

1991

4.2

1977

3.9

2016

6.8

1977

8.0

2011

7.2

2017

8.1