Thank you for the comment, I have searched the web without any result, this table you mention is probably correct for Electrical load FL350 = 75kg,
I am guessing that the difference between Electrical(ground) and Pneumatic load is probably if we are using the APU bleed to feed the packs or not during ground operation
I have those figures for B737 classic APU
-Electrical (Ground) - 75kg/h
-Electrical Load (FL350) - 45-50kg/h
-Pneumatic Load - 115kg/h
According to these figures B737 APU under Pneumatic load has higher fuel flow than average B757 APU on ground.
Any more comments?