1987

8.1

1996

6.4

2007

4.2

2005

6.8

1971

5.0

1975

0.0

1964

7.1

1976

6.0

2004

0.0

1983

5.2

1976

6.7

1977

4.9

1965

5.0

2000

7.1

1993

6.8

1989

7.3

2001

6.7

2003

7.3

2007

6.3

2008

6.7