Calculations on Summarized columns

Anonymous  I see no one has come back with a more detailed reply and I have a bit more time now, so please see attached pbix file below my signature. 

I have created Dimension tables for your for Date, Country and PMN as this will make your life easier in the long run. I referenced the OutboundVolumes table to generate these (see my video on survey data for something similar) but ideally you'd have this in your data source already and can pull into Power BI. 

Then I created a simple measure for Total MB:

Total MB = SUM(OutboundVolumes[MB])

 

Then I created a measure to get Total MB for ALL PMN (when you configure the visual correctly this will give you the total per Country and Date); 

 

Total MB all PMN =

IF([Total MB] <> BLANK(),

CALCULATE([Total MB], All(PMN))

)

 

Finally, I divided these: 

 

% of MB by Total MB all PMN = DIVIDE([Total MB], [Total MB all PMN])

 

Using the Matrix visual, you have your desired column: