We all know that space is about going really fast. We also know that what matters in a collision isn't really absolute speed, but relative velocity. (Two cars with matched speeds on a highway touching each other doesn't necessarily lead to large damage, but if one of them was standing still, it probably would.) A large fraction of the orbiting spacecraft are in prograde orbits, simply because it's easier and, if not actively helpful, at least doesn't hurt; that also reduces the relative velocity between the two.
Yet people keep saying that in-orbit collisions happen at such extreme velocities.
What is the typical relative impact velocity of a piece of orbital debris to an operational spacecraft in low Earth orbit? What are the vector component values of this velocity?
Bonus points for answers that include citations.
Also bonus points for answers that include the data from which the "typical" is derived.