A few thoughts...

Is it possible the CDC estimates are off by half? Two main points come to mind:

* How many Type II errors do doctors commit?

* How many people with the flu do not visit a doctor? People with good health coverage are probably more likely to visit the doctor preemptively when they are feeling unwell, potentially skewing the results.

Also, while google may be off in the exact measurement when compared to the CDC, it looks like the shape of the graph correlates with the CDC data. Overall, this looks approach promising.