Database
[{"continente":"Europa","PIB":1.34},{"continente":"Europa","PIB":1.1},{"continente":"Europa","PIB":1.44},{"continente":"Europa","PIB":1.0},{"continente":"Oceania","PIB":1.0},{"continente":"Europa","PIB":1.30},{"continente":"America","PIB":1.0},{"continente":"America","PIB":2.0}]
Query
db.collection.aggregate([{$group:{_id:"$continente",countSmaller:{$sum:{$cond:[{$lte:["$PIB",1.3]},1,0]}},countBigger:{$sum:{$cond:[{$gt:["$PIB",1.3]},1,0]}}}}])