With stocks you see a rapid increase in the first few years as a company gains traction in their respective market. Thousands of percent increases are not uncommon because the value of the shares are going from pennies to large dollar amounts. After the first few years it becomes almost impossible for any stock to give a thousand percent increase because the dollar amount necessary is just too far out of reach. For example, at a starting price of $900 Bitcoin would need to grow to $53,307 to gain another 5923% increase as it did in 2014. That means an individual trading in "shares" of Bitcoin will need to pay $53,307 for just one. Even the most wealthy, and foolhardy, investors will do a double take on that one. While insane gains are no longer realistic smaller gains are still impressive. From this point forward, I fully expect Bitcoin to stay in the normal growth range for a mature stock.
And at the same time the supply is increasing assuming new coins remain available for circulation.
Here is some more fun with math to make your point. It take an ever increasing amount of capitol to move the price up by the same percentage.
Date Market cap Price Supply
January 4, 2015 - $ 3,856,200,918 $ 281.79 13,684,794
So in this year it took $2,631,749,890 to go up 53% or about $49,655,658 pr percentage point.
January 3, 2016 - $ 6,487,950,808 $ 431.45 15,037,467
Over about the next year it took $7,627,735,314 to go up 104% or about $73,343,609 per percentage point.
December 25, 2016 - $14,115,686,122 $878.81 16,062,338
Source: https://coinmarketcap.com/historical/