How rare is magic in DND?

It might be 6% in Eberron, 0.1% in Faerun and 0.001% on Athas. Equally, there’s the ‘depth’ of magic; 5% of the population of Sharn might be able to cast magic, but it’s only cantrips and maybe a first level spell. However that 0.001% of Athas might be able to reach 9th level magic. 06-Mar-2020

https://www.dndbeyond.com/forums/d-d-beyond-general/general-discussion/59341-what-is-the-standard-ratio-of-magic-users-to-none#:~:text=It%20might%20be%206%25%20in,to%20reach%209th%20level%20magic.