Convert that to GBP and you get about £7.5 million.
Figure that the UK accounts for about 15% of the European economy and assume it contributes to Wikipedia at about an equal share.
That's about £1.125 million in estimated annual recurring contributions from the UK.
You said 10-100/mo, so let's assume £55/mo or £660/year as the mean.
That would be about 1,700 Brits, a surprising number.
Of course, Ireland will have to move out the way. (Wait, is this an actual metaphor for Brexit?)
There are also the various territories of larger countries that aren't - French Guaiana in South America, Canary Islands are off the coast of Africa.