From the chart it is quite obvious that iphone only sell when the price is cheap or free like its competitors (us and japan).
Iphone doesn't sell well at all when there is no subsidies and more expensive than its competitors. Looking at it another way nobody wants to pay a premium for iPhone with similar spec phones can be gotten at half or one third the price.
So apple is only competitive at the free or cheap end of the market.
I think that maybe there is yet another way to look at this and IMHO, a more correct way. First Apple is still selling more phones than last year in the same quarter, so a % Drop does not equate to lower sales. Second, the fact that when the prices perception is the same, people will go to apple says two things --1. if price is equal they prefer the iphone. 2. price is a major driver in the purchasing decision.
I know there are those that think size matters - it does to a some groups, some want big others prefer small, so they wash out in the end. But it is all about price. The majority of the world wants sub $400USD phones. Apple does not make those and therefore does not even compete. However, in the above $400USD market, Apple is actually the best selling phone. The problem is that as the market expands, it expands into the low end, not the high end. Apple will never win in the % of market race. They only win in the quality, ecosystem, and profit race.