I would measure by relative destruction of wealth since corruption is an inefficient destructive process that can quite often yield very little left to steal.
It is all but impossible to calculate how much wealth has been "destroyed" and, more importantly, how much wealth has been transferred from the middle class to the upper class by way of institutionalized corruption that many people, you included, won't even acknowledge as a form of corruption.
Meanwhile, members of Congress are laughing all the way to the bank.