The CDC will be an adequate source for this. I don't know and can't figure out how to find out when they'll next release an estimate of how common ASDs are.

My general experience with this sort of thing is that the dataset will be rich and include many different ways of slicing the data and with multiple definitions, so it's possible to pick and choose numbers to get what you want. Hence, specifying 'CDC' is better than specifying no source of data at all, but to make a good prediction one should specify the specific metric in the CDC surveys or reports.

I am not well-calibrated enough to give good probability estimates and I worry that I'd just be making something up if I tried to give a number. I also revised down slightly from six hours ago considering what you and Yvain have said.

If you can't give a good probability estimate, then no one here will take you seriously nor will you be able to make or accept bets (so no one outside here will take you seriously either). If you want to learn how to do this, my own opinions can be found in http://www.gwern.net/Prediction%20markets

You, who have reasoned that accumulated mutations are a reasonable model, are really not my opponent here.

That's Yvain, not me. I read the recent correlative study like everyone else and find it interesting, but I'm not sure how persuasive I find it.

Fair enough?

If you're really serious about it... What I would've done, if I had this sort of big public statement in mind, is written up a brief precis of why the diagnosis model is right, why I expect diagnosis-driven increases to level off soon (in stock market shorting, they have an expression: 'don't try to catch a falling knife'. When you short a stock, knowing when to start shorting is as important as knowing what is overpriced, because 'the market can stay irrational longer than you can stay solvent'), what my exact metrics will be, what probability I assign over what periods, cryptographically sign my statement, and challenge some prominent anti-diagnosticers to bets on those terms - ideally through LongBets.org for nice round sums like $100, $500, or $1000.

Is this a lot of work? Yes! But you are trying to buy credibility, attention, and change minds down the line; you should not expect that to be cheap or easy.