See the attached workbook showing hot to accomplish this. It took me a few steps and others may have better ideas but I took the Service Dt date field and calculated the difference in days between the first and last date in the field and then used the first date as a value to find the difference between the current date and first date. This difference field is used as the Bins field for 90 days and named [Days since first date(bin)] and used on the Columns shelf.
I then calculated the Sum(Bal Amt) for the bin fields by just using that field to get our 90 day bin values.
next I created a table calculation with the Total() function to get the total for all dates.
finally, I created a calculation that divides the 90 day bin value by the total.
I hope this helps you.
I saved this in version 10.4 for sharing with the widest audience possible.
I hope this helps. Regards and Happy New Years.
Balance Practice+PV_v10.4.twbx 408.0 KB