I was just wondering if anything has been done to the spawn rate of the pigmen spawners, or perhaps maybe the drop rate? It's just a little wierd that I would only have 22 spider spawners and 58 pigmen spawners and yet my spider chests seem to fill up 3 times as fast.

Try going to the nether. The drop rates there are roughly the same as from the spawners. Nothing anyone can do, sorry. <object class="emojione" data="https://resources.enjin.com/1489581540/themes/core/images/emojione/svg/2639.svg?0" type="image/svg+xml" standby=":(">:(</object>

The spawn rate for all nether mobs are a lot slower than the normal world due to their drops.