Worldwide sales would now be approx 3.7m, with shipments around the 4m mark.
With sales almost dried up and under 20k a week you could probably now say that the final sales mark would be 4 million, and that figure would be used in future when someone asks "how much did U2 18 sell?"
I for one was hoping that it would outsell the 90's collection, but it was a case of "ANOTHER best of already?" that hurt sales.
Since it was certified for 2m across Europe i'd put total shipments at around 4.8m (with sales, yes, at about 3.7m).
Of course it only hasn't done as well as the 90's Best Of if we accept (which i do) that MediaTraffic only included the B-Side version of that (to get 3.063m). If not then '18' is actually about 500k ahead, having had a better MT chart run, 2 wks less chart time before Xmas & in a much reduced climate for album sales.