Write-on effect but for a perfect circle

How can you create an animation of a perfect circle being drawn? Starting, say, at the top and being drawn clockwise until the circle is fully closed.

Check the widthpoints side type of the Advanced Outline in the Parameters Panel. Toggle all the handles off, except the width handles. That makes changing things easier.

circledraw.sifz (1.94 KB)

(click on the gif to get the correct view.)