The graph starts when the first iPhone was released. In other words, the tiny number at the left side of the graph was Apple's active base of non-iOS devices up

The graph starts when the first iPhone was released. In other words, the tiny number at the left side of the graph was Apple's active base of non-iOS devices up until 2007. Given the volumes they ship of each, I would expect that the vast majority of the devices in that graph are iOS devices. Macs might bring that number up a bit but the iPhone is going to dominate the average.