, Blue Ink wrote

Another disconcerting fact is that Apple stays almost flat after 2004, in the 20's range; flat enough that it's impossible to say when the iPhone or the iPad were introduced in this timeline. Of course the PC business have been growing in the double digits until very recently, so the graph is kind of skewed, but I was still taken by surprise.

In fact one would potentially expect a substantial drop in Microsoft's percentage share on this graph without it being bad news for the company. Simply if (using oversimplified, incorrect, assumptions to set up an exemplar hypothetical situation) everyone owned one computer, running windows, and then Apple invented the smartphone and over time everyone acquired on of those the Microsoft's market share would reasonably be expected to drop to 50% without that indicating anything negative about the size or health of their market.