[Question] Which way should we update about uncertain events, over time?

If we’re uncertain about the probability of an event x occurring (in virtue of the fact that x has occurred none or just a few times), how should we update our probability of x occurring in the future, in the face of x not occurring over a period of time?

(One example of x may be a nuclear war/​accident.)

Sorry if this is very noobish.

No answers.