1987

6.5

1988

7.2

1995

8.2

2001

7.5

2004

6.6

1997

7.4

1956

7.7

1991

6.8

2001

6.1

1998

6.7

1991

7.6

1986

7.3

2017

7.8

2005

6.7

2017

6.8

2006

4.3

2017

5.4

2001

6.3

2000

5.1

1977

7.0