1999

5.4

1998

5.5

2006

5.7

1996

7.4

1990

6.3

1975

6.1

1971

7.5

2001

6.5

1987

6.0

2003

7.6

2004

6.3

2004

6.5

1995

7.3

1932

7.8

1972

6.0

2009

3.9

2005

6.8

1979

6.0

1970

7.3

1946

4.1