The GUMI report is based on desk research, with figures collected from public sources. However, when certain data were unavailable or unclear, UITP utilised its network of over 1,900 members to gather additional information.
This has resulted in a list of 46 cities included in this first report. Though not exhaustive, the GUMI report covers the globe. Over the coming years the report will be updated annually. In this process UITP intends to grow the list of cities gradually, making the resource even more valuable.