Need Data Of Public Transportation Fares Of Multiple Cities

So, a city where I live has recently decided to quadruple public transport fares and me and my friend group from university are making a study of consequences of rapid transport fares increase. We hope to get a credible correlation model or a heuristic at best. We have already acquired a list of 106 cities with close population density and now we need to get data on the price history of public transportation fare to then see which ones have seen comparable increase. Any additional advises are welcome.