Maybe someone drove quite a while with the parking brake dragging?
Or maybe someone rode the brake alot?
16,000? So expect to do rear brakes about every year on the average? I suspect something wrong.
If they continue to go at 16K intervals I would have to point you to a brake shop that warranties the job for 50K or something. Paying once every 50K is much more like it.
And why did you post this here? This section is for selling stuff.