Well, I looked it up.
Real per capita GDP went from $21,531 in 1980 to $33,599 in 2000. That's in 1999 U.S. dollars.
I think you are forgetting that population also increases, not just GDP, bringing down the per capita measure.
21,000 does not sound unreasonable to me. Remember, it's just per-capita, not per-worker or per-earner.
I trust your number OH. It's just that it doesn't seem like strong enough growth to me.
You are correct about my not thinking of the population going up. (But shouldn't that be proportionate?)