http://www.otcbb.com/asp/tradeact_mv.asp?SearchBy=issue&Issue=EDIG&SortBy=volume&Month=8-1-2010&IMAGE1.x=26&IMAGE1.y=7

Here's the full list thru Aug, but as you point out, not all of them are participants on a daily basis, as evidence of the volume with the lower 1/2.