Calculating percentage

[RingoSun]

I am not quite sure how to word this question so please bear with me! So basically I want to get the percentage value of Client which is 15.26%. I got the table below by just simply choosing the Percent of grand total option.

However I've been trying out calculations trying to get that same value but it keeps giving me 100% instead just like below but the total is showing the value that I want which is 15.26%. 

What can I do here? Apologies if my question isn't clear

[Fowmy · Accepted solution]

@RingoSun 

It's all about modifying the filter context using CALCULATE.
Example: To get the % of grand total by brand would be as follows. Adjust this example as per your data model

Calc % of Grand Total =
DIVIDE (
    [Total Sales],
    CALCULATE ( [Total Sales], ALLSELECTED ( 'Product'[Brand] ) )
)

[RingoSun]

@Fowmy 

That seems to have done the trick, thanks! But just an additional question.

If I put the newly created percentage measure as my Y- axis in a line chart and Month name as my X - axis, I get this line graph below.

Now I know for a fact that the percentage for client is 15.26% so what I want is instead of the line graph amounting to 100% when you total all the months, I want it to amount to 15.26% instead.

How do I achieve that?

[Fowmy]

@RingoSun 

Then you will need to use ALL within Calculate instad of   ALLSELECTED