MeasureKey: "active_users" | "new_users" | "interactions" | "opened_reports" | "resolved_reports" | "tag_accounts" | "tag_uses" | "tag_servers" | "instance_accounts" | "instance_media_attachments" | "instance_reports" | "instance_statuses" | "instance_follows" | "instance_followers"
See
https://docs.joinmastodon.org/entities/Admin_Measure/#key