Great. Thank you.
That's quite interesting. The numbers suggest that if you disregard core Angband (not a variant!) and Sil/ToME (which I'd argue are really separate games more than variants at this point), the five most popular variants are, in descending order:
Of those, the only one I've played is PosChengband. I don't even know what Hengband and FAangband are! Interesting...