1999 Pontiac Grand Prix rear brakes

Just wanted to know if it is normal for my rear brake pads to be replaced more often than the front. I only had to replace the brake pads once since I bought the car and when I did that I put new pads on front and back. Now my front brakes still have a lot of padding left on them. The car does have 4wheel disc brakes if you need to know.

I know the rear pads are smaller and have less padding than the front even when they are new. I just want to know if this is normal.