Create Open PO report with Billed Amounts search as follows:
1. Navigate to Reports > Saved Searches > All Saved Searches > New
2. Click on Transactions
3. Search Title = type a title for search
--Date = on or before XX/XX/XXXX
--Type = Purchase Orders
--Main Line = False
--Tax Line = False
--Status = Purchase Order: Pending Billing/Partially Received, Purchase Order: Pending Bill, Purchase Order: Partially Received, Purchase Order: Pending Receipt
-Number | Summary Type = Group | Custom Label = PO Number
-Amount (Transaction Total) | Summary Type= Average| Custom Label = PO Amount
-Billing Transaction: Amount | Summary Type= Sum | Custom Label = PO Billed Amount
*Add or remove fields as required.
Note: The Amount field with Amount (Transaction Total) and set the Summary Type to Average. This displays the total amount of the purchase order by adding the Amount (Transaction Total) for the all line numbers and then dividing it by the number of line numbers.