I found this for a few characters but they were clearly powerlevelled. That said, yeah 70s I was getting from .5-1% per kill, 80s and beyond it's like... a tenth of that. Beyond 100 and especially 110 you're getting point double zeros.
Sounds like its standard. We tend to forget that at those levels, you could not see the bar move per kill. Grinding 1 level in a day meant getting power leveled.
Literally a full day? Really? You mean you were there 24 hours? /snark People like to say "i was there a full day" but thats zero information content. How many hours?