There's just a few steps now that you've done the hard part.
1) Drag Measure Names to Filter Shelf and choose the 4 fields Percent Medium, High, Low, Critical and don't allow the others.
2) Drag Measure Names to the Colour Shelf of your Marks Card
3) Bring Measure Value to the Angle Shelf of your Marks Card
You will probably want to also display the MN and MV as labels so bring those onto the labels shelf as well. Then you will need to format all four of your fields as %'s you can do this in the measures pane by right clicking, choosing default properties, choosing number format and then selecting percentage.
In this case you could consider using a pivot as well. In this case instead of 4 columns, one each for high, low, medium, and critical. You would replace this with 2 columns one which would contain the old header names; high, low, medium, and critical and the other would contain their value. When doing this method you will not need to use MN and MV and instead could make a pie chart a bit more easily.
Thanks much Carl