content: The system is designed so that the complexity of the calculations required to "mine" a coin increases as more coins are mined. So the more complex the calculations, the more computing power you have to throw at it to get the same mining rate. In the beginning, a decent gaming rig could mine a fair amount of coins/partial coins in a given day. Now that same rate requires an entire datacenter. I've seen reports saying that a datacenter using 50 megawatts will be "entry-level" in the not too distant future.