For example, take the following data, with:

• Recipients
• Sent Mails
• Opens
• Bounced

I want to show the data like this:

• First whole pie for the reciepents. (100%)
• Sent mail (80%)
• Opens (30%)
• bounced (20%)

Note: opens and bounced are the part of the sent slice.

How would it be best to display it graphically. I've thought of using a pie chart, which you can see below.