Formulas for proportion charts on map I try to show pie charts on a map. Each pie chart is a marker for a settlement so the chart size depends on the population. The pie chart sectors contain information about people's nationality. I tried to figure out a right formula to show proportional charts, but I am not satisfied with the results.
Some charts are too big, others are way too small. Sometimes it's even impossible to see the chart or it's information.
Can you tell me formulas which makes good proportions between charts?
I attached a picture to make it easier to understand my problem.

Thanks for your help!
UPDATE: I forgot to mention before, the picture is the result of using logarithm on local population size.

I don't think it's the best solution, but it was fair enough right now. Sqrt ruins the proprotion.
log(sqrt(chartSector1+chartSector2+...+chartSectorN))/C
