1990

6.9

1999

7.4

1967

7.7

1992

6.8

2003

6.5

2009

5.8

1987

5.6

2009

8.3

2006

5.4

1982

7.9

2006

7.1

2007

7.9

2014

8.0

2001

7.8

1991

7.6

2011

8.1

2011

7.4

2017

7.2

2005

7.0

1978

7.0