Not sure I agree it's the basis. What information do you want them to provide you and in what format?
Well, a single example of blanket surveillance having caught a bad guy would be a good start. Or, for a different example, how many criminals were caught with any of the bugs our governments have been oh so careful to keep out of the hands of bad guys like Wikileaks. We can get a lower bound for how many crimes were enabled by not reporting them and having them fixed in some cases by looking at statistics on cybercrime.
CSV would be convenient.