I think there might be quite a jut locked up in dead accounts, especially before when account creation came with Steem, not delegated Steem. The first 500,000 or so created before hf 19 were given a range of Steem at creation, but many of those people and accounts are gone. Then there are plenty who lost keys. 

I normally don't make it to spud either, but I have been unsuccessfully trying to keep a little liquid, before powering it up again. :)