How Common IS COVID-19?

I've had two close relatives test positive for it in the last couple of months, and a third who had symptoms and was tentatively diagnosed with it at a point in time when there was a test shortage.

That's two known and one likely cases out of a grand total of 15 living people composing three linear generations of my family (my parents, me and my siblings and our spouses, our children). One case per generation -- 100% of one generation, 20% of the second generation, and 11% of the third generation.

That I know of.