Expectations of Applause

A question: If you are doing a presentation, what's the minimum size of audience so that you have a (say) 95% chance of being clapped at the end?

If you did one to two people, I think clapping would be unusual. Whereas to 1000 people, it would be pretty certain (if only out of politeness). Where's the middle ground? Where's the turning point?

I'd guess around 12 people, but I have no evidence of this.