1990

6.7

1989

5.7

2004

6.2

2007

6.7

2006

7.4

2016

6.6

2001

7.4

2004

6.6

1997

7.4

1956

7.7

1967

7.5

1992

8.1

1968

6.8

1955

7.8

1995

7.9

1975

7.8

2001

6.3

2009

5.7

1987

6.0

1968

6.3