Apple doesn't have "numerous" facilities. Compared to Google or Amazon they have very few. They really only have two worth mentioning, and having only two is the most expensive thing you can do, with 50% natural overhead.
And comparisons to Google or Amazon are unreasonable, as both these companies sell cloud services. Apple does not.
And it makes sense that the overall size of their facilities would be much smaller than Amazon, Google, or Microsoft... They're not running a major search engine or offering anything like AWS, GC, or Azure.
My spidey-sense is telling me that its very little.