1965

6.8

1995

5.2

2010

5.9

1981

6.6

1971

7.5

2012

8.2

2007

6.2

2017

7.0

2005

7.5

1987

7.8

2019

6.7

2005

6.6

1982

6.0

2009

5.4

2014

5.5

1998

6.0

1997

8.4

2016

8.5

1997

8.3

2020

7.3