The infosession video here (see timestamp around 11minutes30seconds): https://www.epfl.ch/education/phd/edic-computer-and-communication-sciences/edic-computer-and-communication-sciences/edic-how-to-apply/
Also, "How does admittance work?" part mentions that about 40 fellowship were available. Most schools (even top ones like MIT) have around 50% yield rate, meaning that only half of the accepted people take the offer. So, if you have 40 slots, you give around 80 offers. Of course, yield rate is generally around 40% for top-but-slightly-lower-ranked schools (ie, places other than MIT/Stanford etc.). So, 40/.4 = 100