Apple directly reported sales of "services" in the last reported quarter to be 24972M and cost of those sales to be 6485M. https://investor.apple.com/investor-relations/default.aspx

I am no expert, but that seems like a 74% margin on services, which would seem to include their "app store".

It is difficult for me to imagine that apple is somehow incapable of breaking those numbers down into smaller component categories.