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