1981

6.8

2008

6.4

1982

6.9

1987

6.3

2006

7.7

1991

7.5

2004

6.8

1987

7.2

2004

7.1

1996

4.9

1980

5.7

2004

6.5

2005

5.4

2012

4.8

2001

5.6

2006

5.4

2007

6.1

2001

6.3

1999

6.8

2006

6.4