1997

7.4

1998

7.3

2015

7.8

2010

7.3

1998

6.6

2003

6.3

2002

4.6

1982

5.9

2010

6.0

2007

7.0

1997

6.1

1981

6.2

2009

6.4

2012

6.9

2002

6.4

1967

6.6

1991

7.5

2003

7.7

1980

6.7

2014

6.0