20. The apparatus of claim 19 , wherein the means for selecting one of the quota cells from the set at random further comprises means for weighting random selection of the quota cells according to priorities assigned to the quota cells.
22. The apparatus of claim 20 , wherein the means for weighting random selection of the quota cells according to priorities assigned to the quota cells includes: means for associating the quota cells with segments of a segmented bell curve based on the priorities; means for randomly selecting a segment of the bell curve, wherein a segment associated with quota cells of higher priority than those of another segment has a greater chance of being selected than the other segment; and means for randomly selecting a quota cell of the selected segment of the bell curve.