At every level from 1st to 11th, the experience needed to reach the next level (from the current level) increases every level. However, this pattern gets broken for most of the later levels:
- Going from 10th to 11th takes 21,000xp (= 85k – 64k), but 11th to 12th takes only 15,000xp! (= 100k – 85k).
- Both 13th and 14th level only take extra 20k experience each, i.e. the amount needed doesn't increase between those two levels.
- Levels 16 and 17 similarly only need 30k experience each, and 18 and 19 only need 40k experience each.
Why does the last half of the experience chart have some of these levels maintain the same experience costs, and even briefly decrease the experience cost for 12th level?