Got anything on RSS aggregator market share?

Question — While scanning the web to improve my subscribe me plugin, I bumped into a variety of services, such as Pluck, that are candidates for a button. And for the sake of avoiding to pollute sidebars, I’d like to stick to the more important aggregators.

While searching for figures, it quickly occurred to me though that none of the ones you can readily find on the internet are credible. Thus, I’d be curious to know if anyone reading these lines has details on RSS aggregator market share.