I am trying to create a dashboard that, among other things, shows the percentage of issues listed on another worksheet as being completed on time or not completed on time. I want to turn this information into a pie chart with one half representing that which is not completed on time and the other that which is completed on time. I'm having a difficult time thinking of the formula I need to use to show this information.

The chart I'm pulling from has eight columns - IT Manager, Customer Code, Date Opened, Issues, Customer Contact, Impact, Status and Date Completed. As I get a new issue, I complete a row but not all of the rows are completed. Right now I have three entries. None have a date in Date Completed so if I were to show percentage complete it would be 0. How do I create a formula that checks the row to see if it have an entry, then if it does, to check column Date Completed to see if it has a date, if it does, I get a percentage of that which is completed. If it doesn't I get a percentage of that not completed. What is the formula I use? Thanks!