Alright, here's a pretty challenging one!
Taxing 2, 97%, maximum 5 of each skill. (I think with 6 of each, you could do 100%, but minimizing the skill count takes priority over saving the highest possible % here, as long as you're at least reaching the requirement.) I do have a replay, but I might not post it just yet...
Remember that NeoLemmix uses the Amiga version levels, which means there's 100 lemmings in this level, so you're allowed to lose 3 for this.
Aside from that:
Taxing 1 - Should be possible.
Taxing 3 - Should be possible if the time limit doesn't say otherwise.
Taxing 7 - A similar solution to Tricky 4 should work if the time limit doesn't prevent it, but haven't tried yet.
Taxing 9 - Very easily 100%ed with 1 of each.Taxing 10 - Very easily 100%ed with 5 of each, not sure if 4 of each is possible. Can't re-use the Tricky 6 solution as that only saved 80%.Taxing 11 - Something similar to Tricky 7 should work, but more skills required due to the need for 100%. Probably need to direct drop to the exit, as you can't use stoners this time.
Taxing 14 - Definitely possible. Good luck finding anyone who can be bothered actually doing it.
Taxing 15 - This one too.
Taxing 16 - Very easy 99% with 3 of each.Taxing 18 - Almost certain that Fun 11's solution should work here too, but I haven't tried it.
Taxing 19 - 98% with 1 of each. Which should work on Fun 18 too, actually.Taxing 21 - 100% with 5 of each fairly easily. I can't find any way to do 4 - if the level allowed losing one lemming, it could be done, but it doesn't. (This did give me a nice idea for a trick to use in a custom level, though.)Taxing 24 - So damn easy. 99% with 1 of each.Taxing 25 - Fairly sure this should be possible, but not going to try and pull it off.
Taxing 27 - Also definitely possible.
Taxing 28 - 98% with 3 of each. There's several ways to do this, but both 2 skills, and 99% with 3 skills, seem impossible.Taxing 29 - I'd be VERY surprised if the 100% solution from Tricky 3 doesn't work here.
Taxing 30 - 100% with 1 of each is confirmed possible for all 4 WAFDs.