1992

6.3

1982

6.1

1974

6.2

1973

4.8

2007

7.3

1981

6.7

2017

8.5

1977

6.8

1976

5.6

1980

7.0

1996

6.8

1972

6.9

2004

5.9

2006

5.1

2003

6.7

2004

6.7

1993

7.3

1998

7.2

2009

7.3

2009

7.6