An Experiment in Distributed Knowledge

At the suggestion of Cass Sunstein, I’m attempting to replicate an informal experiment he conducted for his book Infotopia. I would appreciate your guesses as to the following:

What is the capacity, in gallons, of the largest oil tanker ever constructed?

Please DO NOT look up the answer. This is an experiment in distributed group knowledge.

Please DO NOT post the answer in comments. Email your guess to me instead. I will keep all guesses confidential, and will report only the set of numbers guessed and various overall statistics.

Thanks for your help.