Not exactly the answer to the question, but I'm able to gather this data from the tax reporting software I use,
bitcoin.tax. I mine into specific wallets that only receive inputs from mining activity. Then I add the addresses in the Income tab on the site and it will scrap earnings off the block chain. I am currently using BTC, LTC, DASH, and BCH addresses. Not sure what if any other addresses they support. You can also download the data in CSV format if you want to do some of your own crunching on it later. Like I said, doesn't really answer how to get the data off ProHashing, but thought I'd share how I report on income in case it's helpful.
