Calculating Percent

Hey Everyone,
I have a report displaying records, the report also shows when they were opened and when they were closed. I grouped them by month and I would like to calculate the percent of records closed within 60 days by month and create a chart of it. Can anyone help?Nevermind, I figured it out.|||Arrgggh.
I calculated percent by using running sums, NumTotalRecords and NumRecordsIn60. The Percent is then calculated by dividing the two running totals, but now I can't chart by that can anyone help???