user12311: For the first four years of bitcoin, 50 bitcoin were being mined per block. There was a feedback loop to adjust difficulty so that blocks would be mined every ten minutes, on average. So why is the graph of "Total bitcoin in circulation" so far from a straight line? See image: 


user23123: When a large amount of hashing power enters or leaves the network, the difficulty adjustments (capped at 4x in either direction) often aren't enough to keep the average block difficulty at 10 minutes. When a lot of hashing power comes into the network, block time is more often going to be less than 10 minutes while the opposite means it's more often going to be more than 10 minutes. This in turn means that coins are generated faster in the former case and slower in the latter.

12311: <p>For the first four years of bitcoin, 50 bitcoin were being mined per block. There was a feedback loop to adjust difficulty so that blocks would be mined every ten minutes, on average. So why is the graph of "Total bitcoin in circulation" so far from a straight line? See image: </p>

<p><img src="https://i.stack.imgur.com/eI133.png" alt="Total bitcoins in circulation"></p>
 23123: <p>When a large amount of hashing power enters or leaves the network, the difficulty adjustments (capped at 4x in either direction) often aren't enough to keep the average block difficulty at 10 minutes. When a lot of hashing power comes into the network, block time is more often going to be less than 10 minutes while the opposite means it's more often going to be more than 10 minutes. This in turn means that coins are generated faster in the former case and slower in the latter.</p>
