If you are dealing with an On-Demand report, you can increase the limit of 15 items, but there may be performance issues, if you set this too high
<CAPC>:8181/pc/center/admin/debug/attrs
OnDemand.MaxItemsSelected.Limit default 15
If this is an "IM Customer View Chart - Table (Top)" view, using the "Interface" metric family, you should be able to display more items, on multiple pages
Notice the page is 1 of 5