Would this help?
Here is what I did:
1. Created 2 parameters for Start and End Dates and assigned the values of 1/1/2016 and 9/1/2016 respectively.
2. Added Date filter as shown below and added it to context. Added Accounts filter to exclude NFE but did not add this filter to context.
3. Created a calculated field named Stats Computed with the formula as shown below. This ensured that I have values for Stats for WFTE accounts too.
4. Next, created a calculated field to get me the divisor as shown below:
5. Finally, a calculated field for the WFTE Ratio as shown below:
A 2018.1 workbook is attached. Hope this helps.
Stats Test Data.twbx 61.0 KB