Data Export to File Pivot: Columns missing due to no data for the specific member

In Data Management/Data Integration, I have a data extract process that utilizes the Data Export to File method to pivot Accounts as column headers (5 Accounts in total). A groovy script runs 3 years of data.

My issue arises when one of those years does not have any data for 1 of those 5 pivoted Accounts, causing the resulting extract file to be different than the other 2 years' extract files. I need to ensure that all files contain all 5 Accounts as columns (otherwise the format of the 3 files will be different), regardless of if there is data or not. Is this possible? Any thoughts on an approach to accomplish this?