This was an idea a customer had for seeing the activity in a group/folder over time. They wanted this for sanity checking - if there was a sudden change in memberships, then there might be something to investigate further. This would be in the More actions, like the current visualization is. There would be the graph, broken down by action type, and form fields for a date range. It would go against the PIT tables instead of the audit log, so it could also show indirect memberships. The direct vs. indirect membership changes should be different lines in the graph.

It could also have an option to export the data as csv.

It should also work for folders, and show counts for all the groups under the folder.