Question Hdd health drops to 70%

Which piece of software is reporting the health percentage?

(There might be some arbitrary yet simple algorithm weighing amount written (TBW) vs. time powered on/days/hours in use, etc., to compute the percentage, and, as 'X' amount of time has now passed, the health status updated, or, possibly some event occurred which lowers the estimate quickly, etc.)

I see my own 500 GB 960 EVO's health is now at 96% Health (as noted in CrystalDiskInfo) for example, after 33 TBW over 4 years of use, and a claimed /logged 10k hours of operation. (I don't believe I've had my rig on 10 hours per day!)