Data as of 2013-06-17 23:45:19 UTC, covering 16384 tweets over 38.72 days.
Includes tweets from 2013-05-10 06:27:30 UTC to 2013-06-11 21:36:35 UTC.
When a reader finishes a book on Kindle, they are offered the opportunity to share this accomplishment on Twitter or Facebook. They can edit the text of what they share, but if they don't, there is a standard format to the text that is posted. This list is generated by looking at recent tweets that fit this standard format and determining which books get tweeted about the most.
This is NOT a bestseller list. This is also NOT a list of which books are read the most. (Although that would be cool.) Instead, this is a list of books finished by people who bother linking their Kindle accounts to Twitter, who also feel like publicly sharing that they finished a particular book, and who do so in a way that doesn't confuse the fairly naïve parsing of the tweets... plus anybody else who happens to post a tweet in the right format.
It is of course also something that is highly vunerable to manipulation. So take it for what it is worth.
But it is fun to watch anyway.