It's not so long when there were "only" 7.7 million of subscribers. And as usually when new expansion is launched the figure goes way up. Which confirmed Activision Blizzard press release that Warlords of Draenor sold more than 3.3 million copies in its 24 hours. And also the publisher announced that the number of subscribers acress all major regions has once again boosted above the 10 million milestone.
Congratulations again :-).