The key on the left is very easy to read and understand, it shows the basic colours and the different area in which the riots were affected.

It is very interactive, as soon as you place your cursor on one of the circles the information relating to that specific area comes up. the information displayed is simple yet effective.

It displays basic information, the user engages more with this layout as you feel like exploring every aspect of this graph.

Looking at the colour scheme I would apply opposite colours from each other so each circle stands out for itself. You could colour code it depending on the area or industry of that workplace.