Ranks the READER axis: which login identities queried the audit trail most within the period.

The response carries the period it speaks for and the total across ALL identities in that period — never the sum of the rows shown. A client that summed a truncated ranking would understate the period by exactly the tail it could not see.

Both denominators are served, so the console derives neither. periodTotal counts every identity in the period; rankedTotal counts only the rows below. rowsReturned and rowLimit say whether the ranking reached its cut. A bar scaled to one of the two totals and printed beside the other is a proportion of nothing.