2006. The site has the actual excel numbers of many other games. Interesting data. By the way, according to video blogger (on Jan 11, 2007):
Blizzard Entertainment announced today that World of Warcraft, its subscription-based massively multiplayer online role-playing game (MMORPG), is now played by more than 8 million gamers around the world.
World of Warcraft has also achieved new regional subscriber milestones, with more than 2 million players in North America, more than 1.5 million players in Europe, and more than 3.5 million players in China.
So it is possible to build a massive MMORP for the metaverse. (well, baring in mind that true Metaverse is a bit more difficult).