Please excuse my ignorance of economics. I recently learned about the Gini-Coefficient as a measure of the economic inequality in a country. I have since seen several plots of this coefficient over time, each for an individual country. The following is from Equality trust and concerns the UK.
Another plot, concerning various countries, is found here:
At first sight, it appears impossible, to construct such a curve for the entire world. Yet, in discussing extreme poverty, I recently learned that incomes can be adjusted to equal purchasing power. Naively it seems, one could measure economic inequality globally. So, are there such data concerning the world as a whole? I know there are maps with countries colour coded by Gini, but this is not what I mean.
My interest is not limited to Gini, if there is another measure, by which the global temporal evolution of inequality can be captured, please tell me!