Utada always used to outsell Ayumi (with some exceptions).
It's true that her sales declined 60% from HEART STATION till her 2010 2nd greatest hits album. I thought that this best could sell a lot more.
It's a pitty for her she used to release cds so less frequently than Ayu cause she could even be a bigger seller than her in terms of total sales. Just think that her debut album sold 7,600,000 copies and is the best-selling album ever in Japan.
Anyway, I'm still glad that Ayu rules the game in overall sales!
As for our beloved Namie, she might sell a lot better than Ayu now but just think that before Ayu released her debut cd, Namie had already sold 20,000,000 cds. And now their total sales are like that: Ayu - 50+ million / Namie - 30+
That means that after Ayu's debut, Ayu sold 50 and Namie just 10 millions.
Namie rules the game now but Ayu was far ahead of her for SO LONG!