Using SWQL to get the snapshots disk usage. This has the same as in built-in widget, but can be customized to include or exclude additional information.
SELECT top 10
,case when SnapshotStorageSize/1024/1024/1024>1 then concat(SnapshotStorageSize/1024/1024/1024,' GB')
when SnapshotStorageSize/1024/1024>1 then concat(SnapshotStorageSize/1024/1024,' MB')
when SnapshotStorageSize/1024>1 then concat(SnapshotStorageSize/1024,' KB')
else concat(SnapshotStorageSize,' B') end as [Size]
,[SnapshotSummaryCount] as [NumofSnapshots]
order by SnapshotStorageSize desc