The last time Mediatraffic (which MJdangerous has contributed some numbers to before) updated GGGB sales was in May 2013 and it was at 8 million. So 8.1 million as of 2010 sounds a bit hard to believe.
I still get so surprised as to how GGGB sold so much. I don't remember Rih being that big those days. If I never joined ATRL, I'd always think Shakira or Fergie ruled that year among the pop gals. I remember Loud being very huge. I always thought that was her biggest era.