1997

6.7

1987

7.0

1981

8.3

1989

6.2

1999

7.6

1999

6.7

2006

7.1

2004

6.6

2005

8.4

2004

6.9

1997

6.5

1985

7.7

2007

0.0

2004

9.0

1966

7.2

1964

6.1

2003

0.0

2002

10.0

2001

8.4

2002

4.5