1927

6.6

1998

6.4

2000

6.3

2010

9.1

2000

7.2

1964

7.4

1980

8.4

2017

6.8

2007

5.6

1994

7.5

2004

7.3

2009

6.5

7.8

2011

7.3

2004

5.8

1997

7.8

1994

6.5

2005

6.6

2010

6.8