Nobody tracks that sort of stuff. We see five of them in our shops, or home tech visits every week... some are 10 years old, some seven, the average is probably five, but we also see a number of them that are barely out of warranty... or still in warranty.
A lot of the time, damage is done by the system in the building not being accurately installed... or bad wiring, or bad Communications Systems or companies... or defective computers... or defective home wiring...
You get a warranty, then you takes your chances after the warranty expires.
I can tell you that in our experience, the LinkSys is among the most reliable... exceeded only by Cisco... DLink is very close. Some brands and models seem to be designed to last only a year or two...
But ask your cable company or DSL provider... They will NOT install any unit that has a high failure rate... and LinkSys is very good, but also very expensive, compared to many in use.