Require help in creating the workflow

Hi Team,

I am designing a workflow with idea like

The data is about students for one year.

There are seven reasons for moving out of the college (ex - Faculty, Facilities etc,)

Now I wanna create a workflow which gives the count of students who left with each reason.

Suppose in month of January if 20 students left with 5 reasons among seven I want the list and those seven reasons should come in the output with count as Zero for reasons which are not there.

I have extracted the data and filtered the columns such as student name, student Id and date of moving out and reason

I have grouped the data with grouping column as reason and aggregation as count.

I got the count of students with each reason for that month.

I got struck at how to get the reasons which are not available in that month data.

How to add them to each month data and their count as Zero.

Please let me know for further details.

Thanks,

Subramanyam Kinthada