I didn't know AKB48 was already officially named the best selling artist of the year for the 2011-2012 time-frame. They'll most likely repeat this success again for a 2nd time.
An interesting fact I might add is that Koda, Ayu, and Hikki are the only female artists in history to win the best selling act of the year award twice. Koda and Ayu are the only ones to do so consecutively.