I thought I'd have to add this in my own analytics call, but it turns out the Dev Center offers an excel export of your download stats that includes the phone OS Version for each purchaser (along with other info like manufacturer, mobile operator, phone language, and somehow even user gender and age group). So I downloaded that report for the last year and found
- 140 users with wp7
- 225 users with wp8
- 78 users with unspecified OS versions (not sure how that works)
looks like over a third of my users are still on 7, so I should definitely make sure the app still works for them!