1997

6.8

1976

7.0

1979

5.6

2007

6.1

1992

5.2

1984

6.3

1984

7.2

2002

6.6

2005

7.4

1999

6.7

1975

4.9

2003

7.2

2006

5.7

2000

6.5

2006

6.9

1991

6.2

2001

6.9

1986

7.3

2007

6.8

2002

5.3