It's kind of a grab bag. If you think of your cube as 2-color decks, hybrids (cast in 70% of decks) are halfway between mono (cast Trained Armoden in 40% of decks, Bottle Gnomes in 100%).
If you think of your cube as 3-color decks, the percentages tip to 90% / 60% / 100%, pushing hybrids closer...