If you'd said about £600 million a year, you wouldn't be too far off. Apparently Google pays Apple some ungodly sum each year to stay put as the default search provider for the mobile Safari search box. Search really does cost the Earth.
It's no wonder Google wants Android everywhere, and Chrome while it's at it. The £600,000,000-plus figure is, of course, a Morgan Stanley estimate for 2014, based on the sheer number of iOS devices out there, but it's probably in the right ballpark. The interesting thing is that back in 2009 Google only paid out £53 million to stay put, which is quite a leap, year-on-year. Also, apparently Google pays out around 75p per pound earned via iOS to Apple, which makes it damn profitable for Apple, and not quite so much for Google.
Now you see why Google spent so much money, time and effort launching Android. It's all about market share, search, data, and money, lots and lots of money. [TechCrunch]