It's worth noting that the results of this poll could be skewed by the fact that it's much easier to for students to give an answer.

I am a PhD student, and I live on about 60% or 70% of my scholarship (though my parents do still pay for e.g. my car insurance; if I also counted all the money my parents spend on me, it'd be higher, but probably still not close to 100% unless I'm forgetting lots of stuff). I picked “about 75%”.

(EDIT: Just noticed that the poll said “need to” -- well, I could in principle reduce my expenditures, but it wouldn't be anywhere near trivially easy for me to do so by a substantial amount.)

I voted 50%, which is correct +/- 10%.

I should note that I could save money by moving back in with my parents and not paying rent, municipal taxes, food, etc., but it's socially expected that I won't do this.