I am going to have to recant I guess. Quickly looking through the IDC, Gartner, World Bank and Strategy Analytics numbers, I can't find something to cite. If you look at global device shipment numbers from 1996 - 2013 and plot shipments per year with a 5 year tailing use to estimate the user base (which seems the norm for the PC user base values) it seems like 15-20% would be closer to the average, not 10% like I stated. I doubt it's important enough to either of us to spend the time to it. ;)

I did a quick check right now and couldn't find it either (always easy to find shipment numbers, but not user base). I am pretty sure it was an IDC or Gartner chart that I saw that showed worldwide pc users per year. Let me do some checking this afternoon when I have more free time and will post a link.