[@MacabreFox] Via city yes. TBF there are probably more mages in the cities as they have the greatest opportunities there. Although not everyone who has the potential to use magic can use it at the same level of proficiency. Also magical abilties do travel through bloodlines. If your family has a history of having mages in your family then it is more likely you will be a mage. 

The Total population of Formaroth is: 21,900,000 (excluding the Desert and mountain tribes). Therefore the rough estimate of magical individuals in Formaroth is around 43,800.

I have yet to do Total population for Beilokias yet. However there are more elves than humans in the world and elves are more likely to inhabit magical abilties than Humans, so if including elves as well the total number of mages would be higher. This actually reminds me I still need to get the magical lore written up :/ .