Just one question, is the "change in accumulated wealth" an hourly value? E.g. if the value was at 0.005BTC steadily over 24h I could assume, that I get 0.005*24=0.12BTC/day ?
Due to the way I obtain the data (not in sync with the actual generation of statistics), this value is per-update.
Currently I poll for new updates every 15min, but sometimes there are no changes, this means that the change would possibly be double for the next update.
Also I am a bit unsure whether the actual numbers on that graph are correct, they need to be verified manually before I can be 100% sure (there might be a decimal-point error, but is _seems_ correct). However the general pattern will be correct.