1983

5.0

1975

3.4

1972

4.0

1980

3.1

2008

6.3

1974

4.1

2005

6.4

2000

6.2

1990

5.7

1976

3.6

1964

6.7

1959

7.1

2001

5.1

2003

6.1

1978

6.5

2004

6.7

2002

5.3

2000

5.0

1981

6.4

2006

4.6