Received Items To Be Billed (quantity to be Billed)

Hello everyone
In erpnext there is an report on stock >Received Items To Be Billed

It has the column “pending amount to bill”,we need “pending quantity to be billed” to be shown on the report .

I have tried with menu>add column but did not get any option there .

I have also tried to export all column form tables tabPurchase Receipt, tabPurchase Receipt Item but did not understand which column need to be added in the query report.

table tabPurchase Receipt Item have a column name as billed_amt ,I hope it also have column billed_qty but unable to get it correctly.

Please help me