Write the opt_per_capita module
Update 14.03.2023: We wrote already some code for it. But as far as I know, we never tested (or even finished?) it for time reasons.
With such a module, the idea would be to generate additional datasets were the input-values are divided per capita, so that you have additional data.
Discussion was also, whether it would be smarter to implement such a per capita calculation in a smart frontend helper. Like this the data would not be saved twice (as practically dividing a variable per population, uses two data sources that exist elsewhere in the database).