Voli: 6 top destinazioni su base nazione associate al maggio

db.parsed_data.aggregate(
{$unwind: "$Segments"}
  ,
{$match : {$and: [
    {$and: [{"Segments.From.Country":"IT" }, {"Segments.To.Country" : "IT" }]},
    {"SearchDate": { $gte: ISODate("2017-03-17T00:00:00.000+01:00"), $lte: ISODate("2017-04-17T00:00:00.000+01:00") }}]}}
    ,

    {
        $group :   {_id : "$Segments.From.City" ,
                    "company" :{$addToSet: {"carrier": "$Segments.Carrier"}},
                    "total" : { $sum : 1 }
        }

    },

	{$sort : {total : -1}})