I didnt know where you have found this data about network hashpower because this is the history:
Once bitcoin cash was activated, the bitcoin cash blockchain stopped growing for several hours, while the bitcoin blockchain continued to add new blocks as normal. This activation happened at 12:37 UTC when both blockchains had just mined block number 478,558—this would be the last common block shared between bitcoin and bitcoin cash. All future blocks would send the coins on their independent trajectories.
There was confusion as the bitcoin cash blockchain stalled at block 478,558. What would normally happen is that a new block would have been mined—478,559—in about 10 minutes. But as hours went by, it became clear that not enough miners were committing processing power to the new blockchain to discover a new block. This was because the new chain also inherited the difficulty threshold for finding a new block from the bitcoin blockchain, meaning a massive amount of processing power would be required.
At this stage, although the chains have split, the new chain didn’t yet have any new blocks, so was technically simply a stalled version of the bitcoin blockchain. Most observers in the bitcoin world thought it would take hours, or even days, for miners to devote enough processing power to the bitcoin cash blockchain to discover a block.
But around six hours later, ViaBTC, a Chinese mining pool based in Shenzhen that has vocally supported bitcoin cash, added block number 478,559 to the bitcoin cash blockchain. This block was 1.9 megabytes in size—nearly double the maximum size allowed on the bitcoin blockchain. Compare this to the same block on the bitcoin blockchain, which coincidentally was also mined by ViaBTC, but was only 272 kilobytes in size. Subsequent blocks, however, have been well below 1 MB, reflecting the small number of transactions on the new blockchain.
Stock split or dividend?

So there is a diference of 474 coins in both blockchains that means that the hashpwer of bitcoin is much more than bitcoin cash. In my opinion not more than 2% of network but maybe I'm wrong