charles andrès (WMCH), 04/02/2015 14:25:
Is there a way to know how many people use Wikipedia per interface language?
No.
Said in other words, I want to know how many people display the Wikimedia project interface in the different version of German and Alemannisch.
Until https://phabricator.wikimedia.org/T58464 is fixed (hopefully in this decade), the requests with non-default language are negligible.* What makes you think that you need such a level of precision and https://stats.wikimedia.org/EN/TablesPageViewsMonthlyCombined.htm is not enough?
Once the use case for such precise numbers is clarified, probably we can extract exact data with a method similar to https://phabricator.wikimedia.org/T65416 after it's fixed (hopefully this year; the bug has made localisation and new subdomain requests practically impossible or unfeasible in dozens languages, for many months now).
Nemo
(*) Even considering the sum of requests with uselang parameter** and of registered users with a non-default language choice in preferences. (**) Even in Commons, despite all the uselang-specific incoming links and the language selection gadget.