If you're talking for this chapter of EG7 specifically, the highest I observed was 60.

If you're talking in all-time Nutaku history, there's the tragically grievous EG2 where some ridiculous SEGs were observed to have over 200m (or was it 100m?) inhibition. Granted it was Dark Airu (and apparently Airu is uncontested OP lore-wise) but it was still ridiculous as we just weren't ready for that. I'm sure that since then the staff have been more than wary about feeding us SEGs that might push us to the point of ragequit.