Honestly, this is something you really never ever need to look at or worry about on iOS. There aren’t good or bad figures for this nor is there any tangible way to improve these numbers as the OS is aggressively handling background tasks and CPU bound stuff. Use the device, it’ll work at its fastest and if it’s hiccuping, reboot it. That’s about it, Apple intends these things to be completely solid state functional devices that always work at their best and they’ve largely succeeded.