@Chris 19 "...android only provides about 20% of their income, compared to 80% for iOS."
I would agree that the acceleration in smartphone ownership that we have been witness to has to a very considerable extent gone Android rather than iPhone (given that it would be a touch unusual for someone to jump straight from a feature phone to a highend phone like Apple's offering) with the consequence that many are to a considerable extent using them as a "feature-phone+". However, that (IMHO) does not take sufficiently into account Apple's traditional demographic which is (whether some of their supporters like it or not) the "well heeled middle classes" in income terms if not that precise demographic in social terms. The last survey I saw of customer groups within "smartphonery" from the States (about ten months ago) indicated that the "typical" Apple customer (ie approximately 50% of their demographic) in the US is male, 25 - 35 years old and lives in a household where the household income is over $100.000 per annum. Given that is the case it seems highly likely that Apple have a larger percentage of customers with significantly above average incomes than the Android os does. In other words the devs do better out of Apple customers because they have more money to spend than is typical amongst Android customers. This of course is hardly surprising since Cupertino have, with considerable success, been courting that demographic for the last two decades or so.