Measure to calculate penetration

[Kasonga2018]

Hi all

I have a table that looks like this 

I am trying to calculate penetration by using a measure, if I have an aggregated matrix view below

I would like to calculate penetration in such a way that segment A is always the denominator, so my final result should look like this.  

[tamerj1 · Accepted solution]

Hi @Kasonga2018 
Please try

Percentage =
VAR Numerator =
    SUM ( 'Table'[Population] )
VAR Denominator =
    CALCULATE ( SUM ( 'Table'[Population] ), 'Table'[Segmant] = "A" )
RETURN
    DIVIDE ( Numerator, Denominator )