1981

6.7

2018

5.8

2004

5.1

1997

7.0

2003

6.6

2003

6.5

1999

6.5

2012

7.8

2001

6.3

1995

7.3

2004

7.1

2001

6.5

2000

7.5

2012

6.8

2000

6.4

2002

7.0

1977

7.7

2016

6.3

2017

6.8

2014

7.7