One question recently floating by me was the number of people groups in need of Bible translations, and especially the number of frontier people groups.
This data is available on Joshua Project. For various reasons, the list isn't absolutely perfect: the question of 'how do we determine if a people group needs a translation' is one full of complexity and nuance that translators and translation orgs are still grappling with. Nevertheless, for a global picture, a 'good enough' answer can be obtained, and graphed.
I used JP's "Definite Need" filter, and then aggregated by my Stage of % Christian levels based on their % Adherent. Here are the results:
Stages: 0, <0.1% Christian; 1, 0.1% to 2%; 2, 2%to 8%; 3, 8% to 32%; 4, 32% to 90%; 5, 90% and higher. Stage 0 = Frontier; Stage 0+1+ "part of 2" = Unreached.
That 'definite translation need' at Stage 5 (>90% Christian) surprised me. But some hint as to the reason can be seen in the two graphs: there is a high count of groups, but a low population figure; this means that we're dealing with a lot of tiny groups. And if you look at the JP Filter, that's what you'll see.
If you have an interest in this subject, I suggest going and playing around with the filters and examining this aspect of the remaining task.