PS4 got 28 million sellers and first 6m seller of the 8th gen before 2015

[Ninsect]

Mr.Playstation said:

In the next month or so it will also have two other six million sellers. For a total of three .

P.S: Kudos on the very clean graph.

It's taken directly from here

http://www.vgchartz.com/platform/69/playstation-4/

You can look at other platforms in the same way