I couldn't find the numbers you wanted. Off hand, I'd guess that the drag on any given pass is probably less than a Newton. You don't want to bring down the orbit too quickly or you could easily lose control. If you watch the video on the Mars Odyssey Aerobraking page, it discusses how the atmospheric drag could change as much as 100% from one pass to the next. After each pass, the vehicle sends back telemetry on things like solar panel temperatures and pressures that gets processed along with the new orbital parameters. The ground crew might have to perform an emergency thruster firing to raise the orbit if too much velocity was removed on any given pass. This is tricky stuff.

MGS also used its solar panels for aerobraking. It was a different vehicle design and the geometry wasn't close to Mars Odyssey so they can't simply reuse the data.