Hi syncop,

You can check all the gas fees regarding the EOS token smart contract here:
https://etherscan.io/txs?a=0xd0a6e6c54dbc68db5db3a091b171a77407ff7ccf

You have all the historic from June 2017 to now.

You will find the fees in the last column.

You can know it was a token transfer as soon you have value = 0 in the value column.

Ah I have to mention that as well, Registering the EOS keys is also done through the ETH network and also cost some gas fees.

T.