http://www.oricon.co.jp/news/rankmusic/43071
According to oricon, Ayu is 4th on the list of the Best-selling japanese acts of all times. Because of Mr.Children's latest album, they updated the top5; so there are new numbers based on sales in Japan. Also this makes her the number 1 female and number 1 solo.
1. B'z (75.614 mil) 1988-now (average: 3.979 million a year)
2. Mr.Children (50.635 mil) 1992-now (average: 3.376 million a year)
3. Southern All-stars (47.083 mil) 1978-now (average: 1.623 million a year)
4. Hamasaki Ayumi (45.528 mil) 1998-now (average: 5.056 million a year)
5. Dreams come true (40.893 mil) 1989-now (average: 2.271 million a year)