// Display the nationalities of artists in descending order by number of artists
DBQuery.shellBatchSize = 1000;
db.Artists.aggregate(
  [ { $group : { _id : "$Nationality", count : { $sum : 1 }}},
    { $sort : { count : -1 }},
    { $project : { _id : 0, nationality : "$_id", count : 1}}
    ]);