1992

6.2

2004

7.0

2008

6.6

2007

6.5

1997

7.8

1997

6.8

1954

7.9

1989

6.4

1970

7.1

1969

7.8

1973

7.4

2003

6.3

2005

6.9

2006

5.8

2018

5.6

1984

8.4

1985

4.0

2000

6.0

1995

5.2

1996

7.7