This counter records the average bit rate of rate-limited traffic through the access port's shaper during the archived historical interval. Reviewing it lets the admin determine whether the port's rate-limiting was actively constraining the subscriber's traffic during a specific past period, versus traffic simply staying under the cap. For example, if a subscriber's speed complaint concerns a particular evening, the admin would check that interval's cmAccPortQosShaperHistoryABRRL to see if the rate limit was actually being hit.