Drill Down within a column chart

Hi experts,

I am trying to achieve Drill Down functionality within a Column Chart for requirement as represent below:

Level 1 having Country name as Category and Level 2 as, say, Cities.

Requirement:

In Level 2 chart, we have to display City name  Country wise and also display corresponding Country name for cities under it.

(see at top of Level 2 chart)

Thanks in advance.