[tor-relays] write-history for exit relays only?

[Philipp Winter]

I want to learn how many bytes exit relays forwarded.  I assume that the
write-history that is published in a relay's extra-info document
includes bytes that were relayed as part of the exit's guard and middle
role?  If so, is there a way to learn how many bytes were written by the
relay in its exit role only?

I suspect that one could approximate this number by accounting for the
probability of all exits being selected as guard, middle, and exit, but
I would prefer a simpler and more reliable approach.