1997

6.8

1999

7.0

2005

6.7

2000

5.3

1998

7.2

1972

3.7

2003

5.8

2005

7.2

2003

6.4

1990

6.7

1976

3.3

2000

6.5

1992

0.0

1995

6.8

1988

5.6

2001

6.9

2004

6.3

2001

6.1

1998

6.7

2005

6.2