db.Borrowing.aggregate([
    {
        $match: {
            fineAmount: { $gt: 0 }
        }
    },
    {
        $group: {
            _id: null,
            totalFineAmount: { $sum: "$fineAmount" },
            averageFine: { $avg: "$fineAmount" },
            numberOfFines: { $sum: 1 }
        }
    }
]);