curl --request GET \
  --url https://api.kit.com/v4/subscribers/{subscriber_id}/stats \
  --header 'X-Kit-Api-Key: <api-key>'

{
  "subscriber": {
    "id": 909,
    "stats": {
      "sent": 2,
      "opened": 1,
      "clicked": 1,
      "bounced": 1,
      "open_rate": 0.5,
      "click_rate": 0.5,
      "last_sent": "2025-01-14T00:00:00Z",
      "last_opened": "2025-01-13T12:00:00Z",
      "last_clicked": "2025-01-14T12:00:00Z",
      "sends_since_last_open": 1,
      "sends_since_last_click": 0
    }
  }
}