Column for status to show "Percent Complete"?

Hello. I am using the latest OO 4 version.

I have a column that I’d like to total to the top level that shows percent complete. For example, if the top level contains 8 children, 4 of whom I have checked off as “complete”, it would be great to quickly glance at the top level to see that I am 50% complete.

Possible?

Thanks.

I agree this feature should be included for Omnioutliner.