Sorry for that misunderstanding. It is only that I suspect the industry could be enormous- only that it is extremely hard-almost impossible- to actually know and quantify what happens behind the scenes(customers orders, financial transactions and so on) and thus quantify its size. In fact the few newspaper articles I have come across can only at the very best estimate the industry's size. For example, yesterday I saw an article in The Telegraph estimating the essay industry in the UK to be worth £200 million(2010).
Perhaps out of naivety, I was assuming that one day, the industry will come above board and act like any other industry.
Or perhaps the whole industry might come to a one, big stop. I have heard university administrators opine that universities might be forced to eventually do away with home work/essays/ dissertations and use classroom based tests as their appraisal methods. However, this approach is fraught with difficulties as dissertations/thesis play a critical role in assessing a student's competency in his/her field(for students who write their own dissertations, anyway).