My numbers are similar. My home desktop computers especially seemed to go thru power supplies every couple of years. After having to replace a motor in my refrigerator for the second time (under warranty) the repair tech said it was a symptom of the crappy quality of the AC power mains: brownouts, voltage spikes, etc.
Once I put every computer on a UPS I stopped having to replace power supplies so often. When I upgraded my home AV system, I put everything there on a UPS also.
I highly recommend that you use a UPS between the wall socket and any high value equipment you operate.
(I still had a power supply fail on a UPS, but it was inside a RAID array, and the power supply inside was a cheap 3rd party Chinese wonder. When I replaced it, I bought an additional spare.)
The only hard drives I've had fail have been very old external drives (>8 years) and one inside a laptop that was dropped while operating.