The circle (including percentage) indicates the percentage of Actions from the Worksheet Lists that were processed today. The Worksheet Lists are a list of tasks (e.g. reminders that need to be sent, telephone actions) that must be completed on a daily bases.
At the start of the working day, this percentage is always 0%. The more actions from the Worksheet Lists are completed, the more the circle fills and turns green. 100% obviously means that all actions for today have been completed.