1981

7.0

2008

8.9

2011

6.1

2009

6.2

2012

5.8

2017

7.6

2002

6.4

2004

7.3

1964

7.2

1998

6.0

2017

7.2

2009

7.1

2013

7.7

1975

6.3

2017

6.8

2004

6.5

2002

6.7

2002

7.6

1993

7.0

2004

6.7