Sentil's solution works, but only until the point where processes are deleted. If you have same requirement as defined on other idea you commented on (), then this won't work.
Once processes are deleted, their associated action items are also deleted. If you need an auditable record of action items retained after processes are deleted, you'll need to copy the action item data to another destination before processes are deleted.
Copying to a custom object ought to preserve the data, make it available in UI and transportable to Jaspersoft DWH using standard Load DWH job.
If you don't need to retain action items from deleted processes, Sentil's solution will work. It requires an SQL based report built in Jaspersoft Design Studio. You won't get this using ad-hoc views/reports.