Where it comes from
The line in the source
2017年12月時点で全世界累計発行部数は3000万部程度 (about 30 million worldwide as of Dec 2017) Explore / Figure
Record
Worldwide cumulative claim, as of Dec 2017
30,000,000 copies (approx) As of Dec 2017
EstimateOur model or estimate. Treat it as an order of magnitude.