[hyxnsfui] Macroeconomic efficiency

A fundamental component of a market economy is a way for buyers and sellers to meet.  Have we gotten better at this, more efficient, over time?

Optimistically, modern technologies like Ebay are hopefully improving things.  However, I could also pessimistically believe that technology is simply allowing those who would pervert the market to pervert even more.  Technology allows economies of scale and larger monopolies.  Any technology that allows a legitimate seller to reach a buyer also allows a zillion deceptive sellers (or buyers) to do the same.  Technology could enable a market but which immediately gets eliminated by new regulations which make the market even worse: using political influence, the status quo blocks change and competition.

Is there any way we can quantitatively measure the efficiency of the market economy as a whole?  In theory, we could measure deadweight loss.