Split rows equally in columns

Hi,

I have come stuck when trying to get excel to split A:A into equal amounts into different cells. Basically eg. A:A will have different racing drivers. I would like the split into different heats. If there is 20 or less then there will be 2 heats with all drivers in each, if there is from 21 to 27 then there should be 3 heats with each driver only in 2 of the heats and 28 or more drivers will be split in the middle, names would need to be taken every other line as the drivers are graded.

I hope this makes some sort of sense.

Thanks in advance
Mark


ps. I have included a copy of the sheet that I have done manually so it is possible to see what I mean.