How many copies of the average set are made/sold?

[arc]

I don't know if any information on this exists outside of the company, but figured I would ask incase any of our historians know anything about this.  My google research yields only a little nugget that says 7 LEGO sets are sold every second. This is extremely unspecific however, so I'm wondering if any more details are out there.

[MAB]

I don't even know what an average set is, let alone how many are made.