Since there's not much of an upgrade path for Android devices in quite the same way I suspect finding numbers to compare against will be hard. Besides, the platform didn't start to really become popular until 2009-ish, so most people are still on their first Android phone.
That stat refers to the first month of sales. I would imagine "normal" people neither time their purchases to coincide with Apple product announcements, nor like to pay early termination fees to be the first on the block with a new gadget.
Theres two other things I've noticed about the phenomena. When an iProduct is launched, my local Apple store has a line around the block on launch day. But then a week later, no line and plenty of inventory. You can just walk into the store and buy one.
When a new major Android phone is launched, there's no line, but it takes weeks on a waiting list to get one and months for the inventory to catch back up so you can just go buy one.
I have a feeling one of the two (or both) is either a manifestation of what we're talking about, or its Nintendo style artificial scarcity at play.
