The Ministry of Agriculture, Forestry and Fisheries publishes regular reports about the tea industry (in Japanese). And the May 2016 report had a breakdown of the tea plant cultivars most common grown in Japan as of 2014.
There are many companies misquoting a certain study examining the levels of EGCG (a specific type of catechin, itself a kind of antioxidant). These companies say that matcha has 137x the level of antioxidants as green tea. In this article, we examine the truth behind this myth.