1980

0.0

1994

3.9

1980

5.7

1975

7.3

1990

7.4

1983

6.7

1995

7.0

2007

7.6

1994

7.2

2000

8.0

1978

6.8

2006

8.2

1996

5.5

1995

2.0

1983

6.4

1970

4.3

1981

0.0

2007

6.4

1990

7.4

2002

7.9

1984

7.5

1984

7.3

2008

1.0

1979

2.5

1989

6.2

1991

5.0

1982

6.4

1989

8.0

1990

2.0

1993

8.4

1981

6.0

2008

5.4