1976

7.0

1970

6.1

2000

8.0

1975

6.3

1998

6.8

2008

7.6

2014

6.4

1978

7.2

1978

7.1

2012

6.3

2000

7.6

2011

7.3

1997

6.8

2011

7.0

1957

6.8

2005

7.9

1990

6.9

2009

7.0

2002

7.7

2020

5.7