KPI Scorecard Month-by-Month Date Range

Hello,

I have a saved search that displays all of my tasks completed (this year to date), and groups them by month with a second column showing the counts for each month (CUSTOM KPI #1). I have a second saved search that displays all of my tasks completed late (this year to date) and groups them by month, with a second column showing the counts for each month (CUSTOM KPI # 2).

I would like the KPI scorecard to aggregate the data ({CUSTOM2} / {CUSTOM1}) and display them on a month-by-month basis (Date Range): i.e.

JAN 95%
FEB 99%
MAR 94%
APR 100%
...
...

My issue is that regardless of the date range selected on KPI Scorecard, the dashboard will only divide the total of all tasks (this year to date) by the total of tasks completed late (this year to day). It doesn't appear to be able to perform calculations on the groups within the saved searches. How can I solve this? Is my issue with the saved search, or the KPI Scorecard?