I have a mostly full record of when servers were added and when they were removed. Let me know what you have in mind in an email or direct message and we can figure out how to get you the data.
There are some edge cases not recorded:
Servers added, removed and then re-added might not be tracked for the period where they were removed.
IPs kept in the system in a “not active” state won’t have a date stamp, but typically they are servers that shouldn’t be added to the pool and are tracked that way so they can’t be).
(This data might also indirectly be available in the monitoring data).