I'd love if there were some sort of data on this, but YouTube doesn't give the data of the pre-share split. You only see the cut AFTER other content ID claimants have taken their cut.
Let me say, however: if you're deciding whether something is worth your time or not based on YouTube ad revenue, then you probably are missing something. YouTube ad revenue should never be your primary source of income from online endeavors. For musicians, for example, I would recommend licensing the song for distribution on iTunes/Google Play/Amazon/Spotify (and here, the question is whether you sell enough copies to make up for licensing/distribution costs).
If you watch most YouTube experts/consultants (people like Derral Eves, Tim Schmoyer, Roberto Blake, etc.,) every one of them will agree on this point -- your main source of revenue should be from things like selling merchandise (e.g., books, songs, albums, whatever), consulting or external services, or so on. YouTube is just one of many tools to build up your brand recognition elsewhere.