gistfile1.txt

    [{
        "$match": {
            "createdAt": {
                $gte:new Date(1479189560111)
            }
        }
    }, {
        "$group": {
            "_id": {
               "year": { "$year": "$createdAt" },
                "dayOfYear": { "$dayOfYear": "$createdAt" }
                
            },
            "count": {
                "$sum": 1
            }
        }
    }, {
        "$sort": {
            "_id": 1
        }
    }]