I'm honestly confused by the point of the question. (I don't mean that snarkily.)
I think it's fairly well-known that self-publishing has a good market share in romance now; and discussing what the
actual market share is might be interesting, if you have some reliable numbers about that. But what's the point of asking about a random percentage? I could post and say, "Will 30 percent of published SFF be urban fantasy in 2-4 years?" and I think most people wouldn't really have any basis for knowing (and probably wouldn't care to guess, when such a random percentage is thrown out). I wouldn't have any idea either (or have any idea what the point of guessing would be), and I'm immersed in the SFF field. (Also, what would this even mean? Titles sold? Titles published? Total revenue?)
Whereas, if I posted an article about how 30 percent of SFF titles published last year were urban fantasy, that would be interesting to people as a market trend. Yeah? (I'm pulling this number out of the air, btw.)
I'm just . . . confused, I guess, as to what you're looking for. I read articles on self-publishing every day (though not romance-specific, as I'm not a romance author), and I know that there are many SPed romance authors, but I don't know what the exact market share is
now -- I don't even think we
have that information, and it's certainly not something I'd know off the top of my head -- let alone how market share trends tend to go. If I were going to examine such a question I'd probably have to do an in-depth economics study of it (assuming the information is available), which is something I've been known to do for fun and is the sort of thing I'd do for a blog series, but not just to answer a poll question. So . . . what are you looking for? Wild guesses? For us to google and see what numbers other people are saying? I'm just . . . not sure.
Also, a couple more points: 1) "market share" can refer either to dollar market share or unit market share and it's not clear which you mean (and if unit share, are we to count free titles downloaded through retailers?), 2) as for the numbers you're quoting, remember that the Amazon Kindle bestsellers are nowhere near the entire marketplace (nor even anywhere near the entire Amazon marketplace, which is itself only a portion of the total market) -- and what are we defining "the market" as, anyway? The U.S. market specifically? Do we count shares of foreign and sub-rights as book-related revenue here, or are we strictly looking at book sales? (Is there a standard meaning out of context when it comes to the book market? I honestly don't know, and am suddenly curious.)
Finally, I want to make a pedantic mathematical note that knowing the market share tells us very little about how SPed authors are doing versus how trade published authors are doing, because we don't know how many authors make up that market share. If a million authors are in category A and 2 authors are in category B and categories A and B split the market share fifty-fifty, you can bet I want to be in the second category.
Also, since revenue streams and how profit is calculated differ for the two groups in this case, that would have to be taken into account if we were looking at which type of
author was doing better as opposed to which type of publishing currently had market dominance, as one doesn't follow from the other. That doesn't mean market share (of either type) isn't
interesting, of course, but I like talking about what statistics do and don't say.
