Amazon sold an estimated 5 million Kindle Fires in 9 months

"Last September I argued against the potential of the Kindle Fire acting as a low end disruption in the tablet market.
Now that the first version of the product has reached is end of life, it’s time to review the discussion.
The first problem is finding out how well the product did. Amazon just released a statement that the Fire accounted for 22% of tablet sales in the US in the nine months it was available. The challenge becomes knowing how many total tablets were sold in the US during this time frame.
Fortunately we know the vast bulk of that total based on the Samsung v. Apple trial. Both Apple and Samsung submitted as evidence sales of the iPad and the Tab product lines in the US. The iPad added up to 16.14 million units (Q4’11 through Q2’12) and the Tab was 540k units. That makes the iPad and the Tab add up to about 16.7 million units. Assuming an additional 1 million units for the other (non-Kindle) total yields an estimate of 22.7 million tablet devices sold in the nine months ending June.
Applying the 22% claim to that total gives a Kindle sales total of 4.987 million. That’s awfully close to a round number of 5 million.
Since Amazon admitted that they ended production prior to launching a replacement (and presumably did so quite early in order to drain inventory,) then we can safely assume that the original production order was 5 million units.
Five million Kindle Fire units becomes the first reliable estimate of Kindle sales (based on Apple, Samsung and Amazon supplied information rather than guesses from analysts.)"

Source:  Analysis by Asymco, 31st August 2012

Note - Kindle Fire has only ever gone on sale in the US