curl --request GET \
  --url https://api.example.com/v1/campaigns/{id}/stats

{
  "data": {
    "stats": {
      "sent_count": 123,
      "opened_count": 123,
      "clicked_count": 123,
      "replied_count": 123,
      "bounced_count": 123,
      "unsubscribed_count": 123,
      "open_rate": 123,
      "click_rate": 123,
      "reply_rate": 123
    }
  }
}