Have a look at how https://en.wikipedia.org/wiki/Wikimania does it. Even here 15 means 2015: https://commons.wikimedia.org/wiki/File:Wikimania_15_Mexico_logo.svg And https://en.wikipedia.org/wiki/COSCUP#External_links is probably representative of the rest of https://en.wikipedia.org/wiki/List_of_free-software_events Anyway, "let's get with the program" please. At least by 2019.