TX fee meaning the gas price * gas limit of a transaction .
Average meaning, how much ETH (or WEI) are people spending on average on a transaction today (May 2017) vs 1 year ago (May 2016) vs the beginning (August 2015)
I would assume the fees themselves have gone up due to gas limit as people increase the gas necessary to interact with contracts, send tokens, etc.
However, there were some periods where the average gas price was much higher than it is now.
Mostly, I'm just curious.
Thank you for your time.