Since Todd's report, here is mine. Started with 100 keys and arrived back this Saturday with 120. Of the initial 100 sent, 30 were removed and exchanged (I made a copy of the initial shipment). From the list, shows that 36 keys in total were exchanged. From the RR's I received from everyone, I got 41 keys for myself.
The majority of my keys that were exchanged were Mississippi issues.