You kinda answer your own question.
Analogous example: if you are an investor and you ask the CFO of a hedge fund: "What is the annual return after fee of your leading fund the last 5 years?". What would you think if he said: "We don't maintain such data. Everything we do here is in a blackbox."
Even if they have some data, you would have to evaluate yourself. If you think of education as an investment, you have to approach it the same way as you would other things.