So now we have 4400 publishers make about 20k each.... considering that out of those 4k publishers some make more than others with average being about 20k it seem like quite a good estimation for our target number of UPS Club members is 4000. Bingo!
Hmm.. when we apply Pareto's Principle to the top publishers, we end up with way less UPS Club Members:
The 4400 top publishers make $89666000 alltogether.
20% of these top publishers (the 880 supertop publishers) make 80% of the money ($71732800).
Leaving only $8966600-$71732800=$17933200 for the remaining 80% of the top publishers (3520)
So the rest will earn $17933200/3520 = $5100 on average.
Based on these numbers, I would guess there are about 1000 UPS Club Members.