App resource usage over time

Looking for a way to collect resource usage (processor, at least) on unrooted OS for running apps over time. This last part is crucial, since there are *numerous* apps presenting *current* usage for running applications, but i’m yet to find one which can generate statistics, collected by running in the background, for used apps over a period of time. Basically my question is a duplicate of this one , but it was last active in 2012 and also never really got an answer for realtime statistics collection.