I have a summary report with a column of late loads per carrier and another with total loads per carrier. I want a 3rd column in % of late loads, Late loads/total loads?
You may find that you need to create a formula field called Late Loads %. Have it calculate to 1 if late and zero if not late. Format it as a Percentage
Then put that in your report and set the Summy to Summarize Averages.