Help with Distintcount logic

[sieed]

I have the following table: 

This table is basically capturing whether a job is finished or not.  I am displaying the job vs date graph below: 




In this graph, I would like to display a tooltip such that: 

- It should display a distinct count of the finishNumber column based on whether the task is complete or not complete. 

   For instance, on 3/1/2017, I have 2 completed tasks and one uncompleted task. The uncompleted tasks do not have finishNumber. So, in my bar graph, when I hover over the red area, the distinct count of finishNumber for the two completed tasks should be 2 ( since 14 and 16 are distinct). And if i hover over the black area, the distinct count should be zero (since there is no finishNumber for the very first record).

How can I accomplish this?  I am not sure what logic to implement and whether it should be a measure or a column? 

Would appreciate any help.