Bowker, the organization that distributes ISBNs in the US and tracks their usage, released an info dump earlier today. They've pulled the basic stats from their last annual report or self-publishing and released it as a series of charts in a free PDF file.
There's no analysis or much in the way of explanation, but the PDF does have a lot of specific details on which service accounted for the most ISBNs usage. And what's even better is that the PDF includes data going back to 2007. Now we can see which service is the most active in which year.
For example, Smashwords was the second largest consumer of ISBNs in 2012. It was handily beat out for first place by CreateSpace (131k vs 90k). The charts also show that ISBNs used for print titles still outnumber the quantity of ISBNs used for ebooks (235k vs 157k).
This data only represents those titles that have been registered with an ISBN, so the data set doesn't offer a perfect view of indie publishing. But now that we have most (all?) of the data that used to be in the paid report, we have a much better understanding of the dynamics of indie publishing.
This PDF is going to be useful, trust me. I don't know all of the ways in which i will use it but data is always useful - even when it is incomplete, inaccurate, otherwise.