Proven reserves in Western countries typically grow at a gentle pace until around the time that production peaks, and then they decline along with production. They represent effectively a kind of inventory - the oil that is close enough to being producible that it can be booked as reserves. Thus they are very roughly proportional to production. There's a bunch of graphs here. Since the OPEC country graphs look completely unnatural, we basically have no idea what is going on. We cannot say for sure how much oil is there or not. The issue is that it goes to the integrity of the reporting process; clearly it doesn't have integrity.

However, in answer to your question, there is no other country that I'm aware of where reserves have grown like that without significant ongoing discovery. So I think it would still look odd, though perhaps less odd, if they had spread it out.