Smartphone market share is not a metric

This isn't really a post about the tech industry so much as one about maths. Or, perhaps, three charts. 

The first shows Apple's share of global smartphone unit sales. Flat, stagnant and, to be honest, slipping. Right?

Hmm. Now look at the same numbers, this time shown as a percentage of global mobile phone unit sales. 

Hmm. Now, actual unit sales. 

Now, let's add Android to this. 

There was a point in time where talking about share of smartphone sales was a meaningful and important metric. That time has passed. It's rather like talking about Toyota's share of sales of Japanese cars in the USA: it tells you something, and was very useful in the past, but not any more. 

There are lots of issues and questions about Apple's future, and lots of different things going on in those charts, including a clear decline in the growth of sales. But 'smartphone share' is not a helpful way to think about those questions.