Yes, but if Android system has makes up 90% of the 90% used, that means that Android system has used 81% of the battery in under 4 hours. That's not normal. I've had similar usage before (but not that bad) and could never figure out the cause. It would just get really hot and the battery would drop like a rock. The only thing that seemed to stop the usage was turning off mobile data, but that's not a very good solution. As soon as mobile data was turned back on, the battery drop started again.
Since then, I have rooted and put a ROM on and haven't had any more problems.