Mozilla probably have that info so readily available that it's not worth publishing it on Wikipedia as well, like on a postage stamp under a filing cabinet in a basement in their gran's next-door neighbour's house ...
Perhaps Moz Corp haven't heard of Wikipedia and so couldn't keep that page updated.
The Mozilla Foundation, being a charity, publishes their financial data on a fixed schedule. If they put the last released data on Wikipedia, something forbidden by Wikipedia for them to do, it would show most of their money coming from Yahoo.