1988

6.3

2003

6.0

1996

6.5

1997

6.8

2015

5.0

2004

7.8

2006

6.7

1962

7.5

1938

7.5

1967

7.7

2004

7.3

1993

5.7

1991

7.2

1980

7.1

2001

5.9

1999

5.1

1974

6.7

2016

7.0

1995

7.1

2008

5.8