1996

6.8

1995

7.8

1999

7.9

1980

8.6

1999

7.0

2006

5.7

2017

7.3

2004

7.5

2009

7.7

2010

6.4

1968

5.7

2015

7.6

1975

7.1

2016

7.1

2010

8.0

2006

7.4

2009

7.4

2011

6.0

2000

8.0

2016

8.6