1974

6.4

1988

6.2

2000

5.8

1996

6.2

2003

5.4

2008

7.3

1992

6.9

2007

5.7

1989

6.8

1985

5.5

1978

6.0

2016

5.8

2000

6.4

1986

6.7

2017

3.4

1994

4.1

2017

7.9

2004

7.3

2001

5.7

2005

4.0