Oricon has released two statistical books – (1) "Single Chart-Book Complete Edition 1970~2005" & (2) "Album Chart-Book Complete Edition 1970~2005". The books detail various artistes single and album sales, from release date to end 2005.
Actually if you think about it, it’s not surprising that our dear 姫 lose out to 山口百恵さん & 松田聖子さん. On average, our dear 姫 released 2-3 single per year in the 80s, compared to 山口百恵さん & 松田聖子さん who introduce one single every three months.
Anyway, here’s the write-up ^^/