You should go check out how many devcoins there are.
To my understanding, there is no target for quantity of PPC unlike BTC. The number of PPC in existence is a factor of the hashing power for POW (more hashing power, fewer coins), the number of transactions that occur (each transaction permanently destroys coins), and time (quantity of PPC grows at a rate up to 1% per year).
It's all pretty arbitrary anyway. PPC is far away from having parity with the dollar.
One of the biggest (maybe THE biggest now?) factors affecting coin production seems to be the ratio of proof-of-stake blocks to proof-of-work. Lately proof-of-work has fallen to as low as 15 blocks per day and may fall further to the hard minimum of 12.