cpu usage storing in influx to estimate coin capacity utilization

This task is related to: https://bugreports.qt.io/browse/QTQAINFRA-4986.
The goal is to create real time statistics about cpu capacity usage and be able to group them by time units.
From the research I done so far - from the point of tracking and visualization - most convenient would be storing cpu_time_used.
The current value cpu cannot be used for many reasons: its stored as string and a tag. Even after transforming data (string to int) and multiplying by duration the value I still cannot be groupped *see picture.

the current view is avialable here
https://snapshots.raintank.io/dashboard/snapshot/RY1UaOyxJBKtp0fCaaZhUgGnPVES4kTr