I'll start the ball rolling and offer up my own RSS Reader stats for your perusal. For the past couple of months I've been using Feedburner to track stats for my RSS feeds. The following graph outlines the RSS Reader spread for people who requested my feeds over a 24-hour period on 17 December 2004.

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The first thing you'll notice is that Bloglines dominates my stats, with over 50% of my readers (apparently) using Bloglines. However there are a couple of important caveats I think need to be placed on that. Bloglines is a web-based RSS Aggregator, which gives it some advantages over the Desktop-based Readers when it comes to stats:

1) Bloglines polls my site more often (on average) than the desktop-based RSS Readers - which most of the others on my list are. So it's likely that the desktop-based Readers are under-represented in my stats. For example, if a NetNewsWire subscriber was offline for a few days during the 17 Dec 2004 period I used, then his/her Reader would not have requested my RSS feed during that time - and hence it would not show up in my stats. I would guess this is a fairly common scenario, as not everybody obsessively fires up their RSS Reader every day (I'm sad to say I'm one of those obsessives!).

2) Related to the first point, it's uncertain how many abandoned accounts Bloglines has that contribute to their readership numbers. With the desktop-based RSS Readers if someone abandons your feed, that will be reflected in the Feedburner stats because the RSS Reader no longer requests the feed. But with Bloglines, it's their server that requests my feeds - not each individual subscriber. So abandoned Bloglines accounts will not be reflected in Feedburner's stats (and there's not much Feedburner can do about that).

So it's clear that Bloglines has an unfair advantage when comparing RSS Reader market share using Feedburner stats. Nevertheless, the gap is so large that it points to Bloglines being the dominant RSS Reader on the Web today. Only probably not by the margin my stats indicate.

Another thing - my total number of subscribers is around 500, which is pretty good numbers for an amateur. But it's probably not good enough to provide a reliable statistical measure for RSS Reader Market Share. It'd be interesting then to find out the same kind of stats from some of the professional or big-name blogs using Feedbuner. Boing Boing would be the most interesting and would provide the best indication of RSS Reader market share. But other professional players like Steve Rubel or 37Signals would also give a decent picture. Do you think we can pursuade them and others to share their stats? I'd love to get a more official view of market share for RSS Readers!