To get an accurate figure of local rates of PMDD, you would need a study looking at daily ratings across a large number of randomly selected women and AFAB individuals of reproductive age. This is quite a large task!
A quality study, completed in the US, showed that the closest figure we have of the prevalence of PMDD is: 5.5% of women and AFAB individuals (of reproductive age).
There is pretty good reason to think that the rates are similar across the world, so you could find a rough estimate of PMDD patients in your country by finding out data from your Office of Statistics (or equivalent) of the above demographic and calculating 5.5% of that amount.