Probably not.
But the data for sales of my novel, Déjà Vu, which I’ve published on the Kindle, iBooks and Smashwords, point to a sales ratio of about 1000:1.
Kindle Sales
Déjà Vu unit sales per month, beginning in March, are: 320, 938, 915, 738, 844, 643 and 581.
Smashwords (this includes Barnes and Noble, and a billion other ebook stores)
For the same period: 4.
iBooks
For the same period: 1.
Overall, then, the ratio of sales Kindle:other is 4979:5. Call it 1000:1. If Déjà Vu is representative of more general trends (it won’t be; but it’s in the ballpark, I expect), the Kindle store could be around 1000 times more successful than the other stores combined. Remember that the blurb, cover image and price are identical across stores.
What Leads to These Differences?
All of my marketing — if you can call it that — has pointed people to the Kindle store.
Amazon has a larger customer base to begin with, so cross-promotion will be more effective. That is, when Déjà Vu is recommended to people who have a history of buying similar titles, there are more of those people around to see the recommendation. It could well be that many people see Déjà Vu on Amazon when they’re not looking for it; few see my book on Smashwords or iBooks.
Amazon has a mature chart-based shopfront. I don’t think Smashwords does this very well. And when I (rarely) look at iBooks, the charts seem to be full of odd books, and they are all written by Jeremy Clarkson. Nothing wrong with that; but it suggests a smaller number of readers.
For the version of Déjà Vu sold on Amazon, I can control the look and feel of the ebook precisely. The version sold on Smashwords is produced using a Word template and, frankly, it looks like a piece of crap. Blockquotes don’t work properly; indentation is shot to hell. Likewise, the version for iBooks looks awful. Now, ebooks aren’t meant to look beautiful — but the creator should be able to provide a well-designed document whose structure melts away so that the reader can enjoy the story.
A Caveat
It’s worth noting that both iBooks and Smashwords are pushing huge numbers of books. Scott Pack recently reported large sales numbers for Confessions of a GP. And my friend Stephen J Sweeney has been selling his Battle for the Solar System books like gangbusters across many platforms. But Amazon has the lion’s share of this market for now.