Why are Namie Amuros sales so high?

[J/TOP2326]

Hi you guys!

Im wondering why namies sales are still SO HIGH?
i think its in another ligue she's playing. ayu can barely reach with an album 54.000 copies and namies single brighter day is already over 50.000 copies.. i mean why? what did amuro do that she is THAT popular? i don't get it and im an amuro fan since 2014 so i cant really talk about her because i havent seen so much from her.
for example koda kumi is also loosing sales. as ayu. but why not namie?