In reply to mr.m.

Do you know that mediatraffic isn't 100% reliable ? Some countries are missing, and Lady Gaga is a worldwide artists. She sold even 100'000 copies in Taiwan (Taiwan isn't counted in Mediatraffic).

UMG reported 6.8M copies as for 2011. So it has surely sold at least more than 0.2M copies in 2012. Thus, more than 7M copies so far.