I'm an ALO, not a BGO, but any moc who does a Principal nomination, probably does it for all their nominations the various academies.
But to answer your question; no, I don't know. Nor do I believe that anyone really knows. I know that it's not many. But "Not Many" is a relative term. There are 535 representatives and senators. So if 10% (53) did, that would seem like "Not many". However; if your senator or representative DOES do principal nominations, then that's all that matters. it doesn't matter what another state's does.