1960

7.4

1965

7.9

1993

8.0

1985

7.8

1990

6.9

2008

8.9

1996

7.7

1997

7.3

2016

8.6

1982

7.8

2017

8.1

2018

8.6

2016

8.5

2001

8.0

1997

7.1

1997

6.3

2006

8.1

2011

8.5

2001

8.0

2005

7.7