Much has been made of Apple‘s (NASDAQ: AAPL) services revenue over the last year or so. After it was clear Apple would struggle to continue growing iPhone sales following the outstanding success of the iPhone 6, CEO Tim Cook commented that a “growing portion of our revenue is directly driven by our existing install base.” That is, sales of apps, content, iCloud, Apple Care, and other Apple Services will account for an outsized portion of Apple’s revenue growth going forward.