I'd like to create a headcount report, where each row is a department and the columns are the last day of each month, for the last 12 months,in Workday. I would like to create something that resembles the table below:
I am not sure how to create the date columns in my report. Could anyone provide guidance on this please? I know there is a field in workday which is "Last working day of each month". This will give me the last working day of this month. However I am not sure how to get this field for the last 12 months.

You may be able to do a Lookup Prior Value calculated field like described in this Community link
Business Object: Trended Workers
Function: Average X Time Periods
Summarization Type: Sum
Field: Ending Heacount
Number of Time Periods: 12
Return Zero on Error: Yes