1998

6.3

2004

6.8

2006

4.3

1986

6.6

2003

6.4

2005

6.6

2006

5.2

2005

6.1

2002

6.0

2000

6.4

2006

7.6

2006

5.4

2001

6.3

2006

5.4

1988

6.2

1989

5.7

1989

6.7

2002

5.1

1971

7.2

1993

6.4