Since I once got the report when I only used 150kwh and was saying there were other people more efficient than me, I assure you it's looking at vacant apartments and houses.

Also it's downright stupid to waste resources and postage to mail people who aren't offenders and can do little more to optimize their power use other than turning off the mains.

Just mail worst offenders, people above the averages and save hundreds of thousands of dollars on what becomes junk mail.