Active accounts, though? A lot of them would probably not be. Not to mention people that create hundreds of bot accounts for their resteem services, etc. I guess I can't think of a parameter to filter those out. Even amongst what @penguinpablo calls "accounts transacting" (including all those bottish 3 SP accounts) the percentage should be a good bit more. I'll look forward to the post.
Also, it's worth noting that in the scenario of adoption many more people would buy STEEM if they could use it to buy groceries and do everyday tasks with it. So the average fiat value of accounts would likely go up.
You make a good point. The information should definitely only include accounts that have been active within the last month or so. This would create an accurate picture.