Anyway, I'll split that time in different periods as you say and see what's going on, but I suspect the graph is showing profits before fees.
No. Its not. Graph shows actual profit paid out to investors after fees. There is one issue with graph that I am aware of... bankroll size isn't 100% precise on graph as we don't store it in database every day, but we show sum of all active investments on that day including todays profits (active investments change all the time...). Graph is more for informative purposes.