How many active Klingon speakers are there?

Question

I am well-aware of the fact that some people use Klingon in conversions at special conventions and events.

Is there an estimate about the number of Klingon speakers and how many of them are there?

Answer 1

According to Wikipedia, about 20 or 30 fluent speakers

Another more interesting article, a bit more scholarly, mentions a wide variety of numbers per study.