How does University of Michigan distribute points required for admittance?

I know that 100 points are required for admittance. I also know that University of Michigan used to give minorities 20 points automatically, that's one-fifth of the points required for admittance, to keep there student body diverse. I don't think they do that any more. But what determines the number of points distributed to a student applying to University of Michigan (ACT, GPA, etc).