curl --request GET \
  --url https://api.hubapi.com/marketing/v3/emails/statistics/histogram \
  --header 'Authorization: Bearer <token>'

{
  "results": [
    {
      "aggregateStatistic": {
        "counters": {
          "bounce": 0,
          "click": 8,
          "contactslost": 0,
          "delivered": 704,
          "dropped": 1,
          "hardbounced": 0,
          "notsent": 1,
          "open": 443,
          "pending": 0,
          "selected": 705,
          "sent": 704,
          "softbounced": 0,
          "spamreport": 0,
          "suppressed": 0,
          "unsubscribed": 0
        },
        "deviceBreakdown": {
          "click_device_type": {
            "computer": 6,
            "mobile": 2,
            "unknown": 0
          },
          "open_device_type": {
            "computer": 44,
            "mobile": 8,
            "unknown": 391
          }
        },
        "qualifierStats": {},
        "ratios": {
          "bounceratio": 0,
          "clickratio": 1.136,
          "clickthroughratio": 1.806,
          "contactslostratio": 0,
          "deliveredratio": 100,
          "hardbounceratio": 0,
          "notsentratio": 0.142,
          "openratio": 62.926,
          "pendingratio": 0,
          "softbounceratio": 0,
          "spamreportratio": 0,
          "unsubscribedratio": 0
        }
      },
      "interval": {
        "end": "2020-06-01T04:00:00Z",
        "start": "2020-05-01T04:00:00Z"
      }
    },
    {
      "aggregations": {
        "counters": {
          "bounce": 1,
          "click": 0,
          "contactslost": 1,
          "delivered": 4,
          "dropped": 1,
          "hardbounced": 1,
          "notsent": 1,
          "open": 4,
          "pending": 0,
          "selected": 6,
          "sent": 5,
          "softbounced": 0,
          "spamreport": 0,
          "suppressed": 0,
          "unsubscribed": 0
        },
        "deviceBreakdown": {
          "click_device_type": {
            "computer": 0,
            "mobile": 0,
            "unknown": 0
          },
          "open_device_type": {
            "computer": 0,
            "mobile": 0,
            "unknown": 4
          }
        },
        "qualifierStats": {},
        "ratios": {
          "bounceratio": 20,
          "clickratio": 0,
          "clickthroughratio": 0,
          "contactslostratio": 20,
          "deliveredratio": 80,
          "hardbounceratio": 20,
          "notsentratio": 16.667,
          "openratio": 100,
          "pendingratio": 0,
          "softbounceratio": 0,
          "spamreportratio": 0,
          "unsubscribedratio": 0
        }
      },
      "interval": {
        "end": "2020-07-01T04:00:00Z",
        "start": "2020-06-01T04:00:00Z"
      }
    },
    {
      "aggregations": {
        "counters": {},
        "deviceBreakdown": {},
        "qualifierStats": {},
        "ratios": {}
      },
      "interval": {
        "end": "2020-07-02T00:00:00Z",
        "start": "2020-07-01T04:00:00Z"
      }
    }
  ],
  "total": 3
}