1955

6.0

1999

5.6

2002

6.7

2006

6.4

1986

8.0

2002

7.1

2001

6.2

1996

6.8

1980

3.6

1965

4.6

2006

6.5

1997

6.9

1996

2.7

1979

8.2

2004

5.9

2007

5.2

2005

6.5

1987

7.5

1996

4.0

1990

6.3