1985

6.3

2000

7.0

1974

6.2

2001

6.6

2003

8.7

1990

5.7

1986

6.7

1976

8.0

1998

7.4

2001

6.0

1969

7.3

1992

7.2

1988

8.1

2006

4.0

1999

6.5

2000

6.4

2007

7.0

2003

0.0

1990

5.6

2002

6.9