[ProDigit]

@JD Gumby: They seem to be overlay charts, not regular charts; kind of like one chart layed on top of the other. They used the wrong format there, but perhaps their numbers are more accurate than the graph shows.

If in the above picture the light blue are tablets and tablet-likes, and the dark desktop pc's and laptops, then there are about 40 million tablets sold at this time, and 100 million pc's. Not 150million (just to illustrate overlayed).

Another thing that's not mentioned, is that it could add on the previous year results (meaning counting total sales so far, not yearly sales)... Just saying there are indeed many ways to interpret the graphs.
In any case, I found it an interesting read. If not, just for what the original writer saw, even if it may be totally different from the way we perceive the world around us.