It's fairly easy to guess the full extent with a tolerable awareness of history and human motivation.

1. Pedos in power who can have anything they want, get anything they want, do anything they want... do. And they aren't grasses, you hear?
2. The truth is it's not so much pedophiles. Yep, you heard me right. Not pedophiles. Then why are they sexually abusing children? These are largely people who've plumbed what they imagine to be the depths of heterosexual, consensual intercourse and are seeking new novelty in highly charged situations in which their control is unchallenged. This is nowhere more true of they who look to Rome yea even unto Babylon for moral inspiration in the new age of empire; the elite entitled by almost divine right to any kind of gratification and aggrandizement yet dreamt.
3. And then there's a deeper reason: dissociatively altered states, that's where the real novelty kicks in, doing things your old self would never have imagined as possible, it opens up a new world of the mind. This is classic LHP and isn't just the domain of misfits and morons like Crowley flaunting their deviance.
4. The role dissociation plays in arcane rites of passage and repugnant acts play in establishing bonds of secrecy necessary for esoteric societies. Yes, those. They didn't go away and they aren't make-believe. The elite finds esotericism a meaningful respite from the confused rigors of the world, a way to reimagine their temporal power as having metaphysical basis. I don't believe any of it, but they - many of them, at any rate - do.
5. The secret services find child abuse dirt and other blackmail items politically useful. The national interests are, in this way and others, upheld as best one can in an increasingly internationalized world - at least, for the section of the services which believes in the national interests and not other more nebulous ones.

So, these factors being so, you can safely say that a fairly huge chunk of the elite are involved in this, and that a great deal of global flesh trafficking is diverted thereto. Only the minor idiots and bottomfeeders like Savile have abuse patterns that are easily dug up - the more powerful and wealthy simply don't need to employ the "underage subnormals" as ensconced in psychiatric and educative institutions. They don't even need to attend honeytrap sex parties. No, they have their own gigs safely subterranean and away from the prying eyes, not of the media, but of the watchful others.