A Percentage attendance number

I am trying to calculate overall percentages in a Pivot table and not having much luck. In my attached fictitious workbook I have two tabs. The "raw data" tab contains names and whether they attended a Math-101 class. If *they did* attend the class then the date that they attended is entered for that student. If they did not attend then their cell is left blank. As you can see by my example, 4 people have attended.

The Pivot table I'm building is in the tab labeled "Pivot." I dragged Name to Rows and Math-101 to Values. Notice the Grand Total is 4. That's great but what I really need is an additional column, (or something) that says 40%. I'm trying to convey information that shows this class had 40% attendance."Is there a way I can do this in the Pivot table itself and not by doing an external calculation? Thank you.