1953

7.2

1991

5.7

2010

5.2

2006

6.8

1998

6.0

2016

6.7

2017

6.6

2001

6.8

2011

7.5

1965

6.3

1976

6.2

1985

6.1

2000

5.1

1994

6.1

1980

6.6

2003

6.8

1971

6.0

2009

6.0

1988

6.5

1999

6.6