As I said, iOS 8 reached 92.5% user penetration in the same month after being in the field less than 11 months.
Even your chart doesn’t tell the whole story: Those Android named releases are the base version of the Google OS and don’t take into account the “value-added” specific distributed releases pushed out by the major service carriers to their subscribers. This adds another level of complexity: Your Android version is the base Google release PLUS the phone manufacturer release PLUS your specific carrier version. But the time it gets to the end user, you’re running a two year old Android version unless you buy brand new on release day at your local phone store — and for the reason below that version will pretty much be the only version you ever have on your Android phone.
You can’t just load the new Android OS onto your Sprint/AT&T/Verizon/BellSouth Android phone without jail breaking it, and the cell service providers have vested interest in never giving you the next major release when they’re trying to unload their inventory of new phones running the latest Android OS. When I was an Android user with a Samsung Galaxy IIs phone, it took Sprint PCS a year to finally release a version of Froyo tailored for Sprint with their crappy bloatware that was more than a year out of date once it finally came via OTA upgrade. Then they ultimately had to roll it back because it radically shortened battery life thanks to a hideous memory leak that kept background apps running at 100% activity. Just awful. Sprint PCS responded with “Why not use this chance to come in and buy the new Galaxy III and renew your two year contract?”. I looked at what the “brand new” Galaxy III was running and it was a version of Android that came out in Spring of the previous year.
That was when I switched to iOS. Never looked back.