How to make a RTC OOTB chart using Team Area data (work item statistics widget)

I am trying to utilize the OOTB work item statistics chart to show "active number of task by team". The Team Area is not on of the available options for this widget.  The reason I can't use categories is because each team has many associated categories.


For reference...the following sample team structure and associated categories is explained below:
Team 1                     <-----There will be 12 different teams
  - CAT1                    <---Total categories will be around 100
  - CAT2
  - CAT3
Team2
  -CAT4
Team3
  - CAT5
   -CAT6