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Most of those in the US, but with a lot in the UK and a few in Germany.
However, I haven't noticed any spike in the number of my other e-books being sold on Amazon.
Maybe this doesn't prove anything one way or the other about the value of this marketing technique, since those who downloaded the free copies probably haven't had time to read them yet.
Or they've read enough of the book to know that they don't care for it, but I'm trying not to think about that. 
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