Apple bought in an existing expert ARM licence SoC design company. The first iPhone used the Samsung SC6400 family ARM SoC.
Also on what basis is this assessed? Apple doesn't have even a quarter of mobile phone market. What about chips in washing machines, router/modems, TVs, Radios, Flash (used in phones, eReaders, USB sticks, SD Cards, HDD parameters, modems, TVs, etc), RAM.
Really this sounds dubious that Apple was ever at #1. Also what foundry makes the chips that Apple's bought in company uses?
Also "sales value" for chips only used in house might be quite fictitious.