https://www.forbes.com/sites/ellenhuet/2014/07/02/ubers-newe... (2014)
https://www.washingtonpost.com/news/the-switch/wp/2016/08/23... (2016)
https://qz.com/940605/is-the-era-of-cheap-uber-rides-over/ (2017)
But I don't have a breakdown per-market.
There was a really detailed breakdown posted somewhere on HN a while ago but I don't have it offhand.