It's not per donor. Their total transfer volume last week was €1,589.34 according to the website. As far as I can tell, the only project with more than €100 in weekly income is Liberapay itself.
EDIT: I see now that they cap donations per donor and recipient at €100 per week, but it doesn't seem like anyone gets close to the cap.
EDIT: I see now that they cap donations per donor and recipient at €100 per week, but it doesn't seem like anyone gets close to the cap.