Within the context of this article, the description provided seems fair enough. It obviously refers to surface area (as in: square miles).
Of course, if you think that they might really mean "pre-tax revenues minus deferred depreciation per worker" or such, you are free to do a little investigating for yourself.
Track down leads, contact the author, rough up a few witnesses, go over the crime scene with a fine-toothed comb, etc.
Regards,
Real snarky. But we’ll done snark.