Calculating Population-weighted Atkinson index in Excel

#1
For my dissertation, I am calculating inequality on a worldwide level, between countries.
In my calculations, I would like to give each country a different weight according to the share of population they have in the total world population.

So far, I have had no troubles in finding weight-adjusted formulas for the coefficient of variation and the Gini index.

My thesis-advisor would also like to see the Atkinson index in my final paper, but I cannot seem to find any formula that shows how to incorporate weights in the index. Is this simply because of the nature of the index, or does it have something to do with decomposability? There might be something that I am missing.

I plan to use the values 1,2 and 4 for the inequality parameters for Atkinson.

I am performing all my calculations in Excel, but if necessary, I have access to SPSS and Gretl.

Thank you in advance for your help.