Unfortunately, Shenmue didn't sell more than Sonic Adventure, as you see here:
http://web.archive.org/web/200407141818 ... ank_d.html
BTW, Shenmue II is the 20th game in that ranking.
Anyway, SEGA says first game was sold more than 1,200,000 copies worldwide.
http://www.digitalrex.jp/ys.html
Do you see "120万" at the bottom left? That means 1,200,000 in Japanese.