Hello,
nice chart. There should ne a correlation to how much it has cost in USD to have that much mh/s.
In the days before the gpu miners this surely would have been quite expensive.
This is the right idea. Any chart like this has to be standardized to one particular setup - and therefore a particular hardware depreciation rate and MH/Watt. Also, as mentioned above, there have been "epochs" where the available processing tech has changed, so back-dating across multiple epochs is tricky. Within epochs, there is still movement too, just not as jumpy.