How much aerodynamic drag does each component contribute? Obviously numbers will vary based on the specific bike, but what are some approximations of the drag contribution of individual components in a typical (non-aero) road bike?

I have read in many places that the rider accounts for most of the drag. So obviously, riding in a more aerodynamic position is free speed. But after that, what are the most significant upgrades to the bike itself, and how large might those gains be?
I believe this is a hard question to answer because there are many interactions between different parts of a complex shape like a bicycle and rider.

At a guess, I'd rank components by frontal area and position toward the front on the bike. For instance the rear wheel has less effect that the front wheel  because it is moving through disturbed turbulent air.