Mine's mostly standardbred with a little bit of percheron. He started out as a frankenhorse. Actually I thought he looked like a Tyranhorsus Rex. HUGE head and shoulder with stumpy legs and a truly swayed back.
So I would say some of them have a little standardbred in them.
This is the closest shot I have of him. This was a 1 1/2 after I got him, doing novice. Still had a weak back and used the underside of his neck.

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Average, for horses with some experience at this level