Normal distribution, truncated at zero ... mean 10, standard deviation 50.

And that's ten and fifty I mean, not one hundred or five.

Edit: Justification is a sense that there are less than 1e4 people on ice so far, suspected to be based on flipping past such a statistic on a webpage without consciously reading. Expect number of people signed up is between twice and thirty times number stored.

Edit mk. 2: Or between zero and twenty, whichever is greater.

Edit mk. 3: I have now checked my numbers. ...Interesting.