I recently saw a contributor that has a couple hundred images and over 100,000 downloads. I wouldn't call that average. I'd say that's some spectacular performance and exponentially above average. Could they have deleted thousands of images? Maybe. Looking at their work, I doubt it. Excellent, well edited, highly sellable stuff. I'd guess they have a massively high RPI and $10 wouldn't surprise me.
Above average and exceptional work.
So what's the average RPI?

(devils question because we don't know who or what or how many images, but I suppose on the large scale, the survey could come up with an average, average?)
If I was getting $1 a month I'd be exceptionally happy. Keep in mind that I'm only with SS and IS now. Some people are marketing through 25 or more agencies, maybe their own sites? It's a tangled web for such a simple appearing question.
So far 52% of the people who answered make under 75c RPI per month. We don't know if those same people have 300 images on two sites or 3000 images on ten sites.