yeah i know.... that's what i thought as well. the only thing i can think of is that not everyone gets a uai (doesn't want it/dropped out) but i think the uai percentages are allocated as if everyone who did the school certificate also applied for a uai, whereas uncle med considers 10% of the people who did the hsc, which is a smaller number. don't ask for a source, i couldn't name you one, but that's the only idea that jumps to mind right now.
still, i'm sure about it being 93.8...