Calculating market size when more than one branch in the same local market

[CloudMonkey]

Hi,

Please can you tell me how to calculate the market share for each of the below markets? e.g. for London the market share is 1.944% ((142 + 274 + 195) / 31425). My target output table is the first screenshot below and my input data is the second screenshot below.

Thank you for your help,

CM

[HotChilli · Accepted solution]

A measure like this

Measure = SUM(Table[sales]) / MIN(Table[size])