Brad Guigar, creator of Evil Inc., just posted these results of a survey he did of his reading audience. It's a sampling of just his comic, of course, but it there are some interesting and unexpected (to me) tidbits. The one that most caught my eye was this...
All of his other data points to a viewership that seems pretty typical of comic fandom as it currently looks in America: mostly college-educated males between ages 25-44. Marvel and DC figure prominently into their reading/buying habits, and they're more interested in t-shirts than posters or calendars. But the so-called "Wednesday Crowd" isn't nearly large as I would've thought. Even if you wrap up the Thursday, Friday, Saturday, Sunday folks into the mix, it barely accounts for a quarter of his readership. Almost half don't buy comics AT ALL.
The survey does not get into whether they're downloading them illegally, but the follow-up question ("Which publisher do you tend to buy more from?") points to only around 20% of the respondents saying they don't read comics at all. (I'm presuming they're only talking about printed comics; I have a hard time seeing that 20% of respondents to a survey run by a webcomic didn't actually read the webcomic itself!) These two figures suggest that about 25% of his traffic read ONLY webcomics.
Evil Inc. isn't really typical fare when it comes to webcomics. It caters more to a Marvel/DC fanbase than probably a majority of webcomics, who tend not to try to directly "compete" with those two publishing giants. But it provides a fascinating study of the crossover area between "traditional" comic purchasers and their digital counterparts.