Filter geomaps report data

Hi,

This video explains how to use geomaps reports. Unfortunately, I couldn't figure out how to create a filter that makes it possible to select subsets of data in the top left corner of the report (in this example its "top 25 cities"). Neither have I fould a solution in the corresponding web tutorial, nor did the BO mobile report designer's guide help me solve my problem.

Any recommendations?

Thanks,

Sebastian