How can I create a list of people with perfect attendance?

1. Go to the Rosterizer pane
2. In the Included Volunteers tab, click on "Include only volunteers that pass this filter..."
3. On the left of the Filter window, click "Assignments"
4. Choose "Did not show up exactly 0 times". 
5. Fill in "Between the dates of [date] and [date]"
6. Then click OK.

Now the roster you generate will only include volunteers with perfect attendance.