1968

8.1

1995

7.6

2000

8.2

1959

7.8

1991

5.0

1994

7.9

2001

7.8

1979

6.5

1984

6.0

2007

8.8

2017

5.5

2015

5.5

1932

7.3

1997

7.6

2005

4.6

1986

7.6

2006

5.7

1995

8.4

1955

7.9

1974

7.9