You can find this report by going under Reporting / Items / Top Silent By Bids on the left-hand side of the auction manager.
Top Silent By Bids
This report is a break down of the top silent auction items by the number of bids they received. In this report, the items name, the item's category, the number of bids, starting price, ending price and percentage gained are all displayed.
The percentage gained is going to show the percentage that the item gained from the starting price to the ending price.