[formerly_proven]

"CPU usage" as in "how many time-slices did this process eat?" is pretty easy to understand and generally points at the right things ("What's eating all that CPU?", "Is this application using the correct number of threads?" etc.)

Trying to express "How much of the hypothetically available computational resources of the CPU did this application consume?" in a single number would seem like a futile exercise at best. VTune used to have something like this which IIRC was based on using all cores in parallel sections and IPC or something like that. It wasn't very meaningful, and is impacted by all sorts of factors.