Ability to report on average time articles spend unverified/awaiting review

Feature Request Summary: 

I would like to have the ability to report on the average time articles spend unverified and awaiting review.

Even just having the ability to query article time spent unverified/awaiting review in Explore (from the Guide dataset) would be helpful!

Description/Use Cases: 

From a content management perspective, I'm looking to measure the efficiency of our content curation efforts. It would be helpful to be able to show that a documentation team was able to down drive down and maintain this metric below a set KPI.