Struggling to create a "% of Distinct Count of StudentID" measure in DAX

[Breen]

I am tasked with emulating a Tableau dashboard. I have successfully created the visuals that look the Tableau one, but the Tableau has a Mark/custom column called '% of Distinct Count of StudentID', which details the percent of Student divided by the total number of Students for that year. For example, the visual details '300' students, in "Points Earned" bracket '34', during Year '2018'. "Year" is along the X-axis, with "Distinct Count of StudentID" (counting the number of students) on the Y-axis, and "Points Earned" as a Legend.

I need to create a DAX measure that calculates the % of students from a 'Year' and a 'Points Earned' bracket against the total number of students from that Year. For example, '300' students, in "Points Earned" bracket '34', during Year '2018' divided by '4000' total students from '2018', should give 7.5%.

My current DAX is: 

Percentage_UCAS_CC =

DIVIDE(

    [StudentIDs],

    CALCULATE(

        [StudentIDs], --A measure

        'DataSource',

        'DataSource'[Year],

        'DataSource'[Points Earned],

) * 100

TL:DR - Need help making a DAX measure that calculates: Number of Student ID / Total Number of Students for each Year (Percentage format)

Any help would be greatly appreciated.

[Fowmy · Accepted solution]

@Breen 

Bsed on the limited details, I modifed your measure assuming you are using the Year and this measure on a visual like a table visual. 

Percentage_UCAS_CC =
DIVIDE (
    [StudentIDs],
    CALCULATE ( [StudentIDs], ALLSELECTED ( 'DataSource'[Points Earned] ) )
)

[Breen]

This worked perfectly, thank you!

[Ritaf1983]

Hi @Breen 

Please provide sample data that covers your issue or question completely, in a usable format (not as a screenshot).
https://community.powerbi.com/t5/Community-Blog/How-to-provide-sample-data-in-the-Power-BI-Forum/ba-...
Please show the expected outcome based on the sample data you provided.

https://community.powerbi.com/t5/Desktop/How-to-Get-Your-Question-Answered-Quickly/m-p/1447523