That ~20% varies by year but is still ~1.5 Billion dollars per year which is a major studio representing a long tail of properties that come out infrequently. More importantly you need to consider future franchises not just their current properties:

Caesar, Crash Bandicoot, Diablo, DJ Hero, Empire Earth, Gabriel Knight, Geometry Wars, Guitar Hero, Gun, Hearthstone, Heroes of the Storm, Hexen, Interstate ’76, King’s Quest, Laura Bow Mysteries, The Lost Vikings, Overwatch, Phantasmagoria, Pitfall, Police Quest, Prototype, Quest for Glory, Singularity, Skylanders, Solider of Fortune, Space Quest, Spyro the Dragon, StarCraft, Tenchu, TimeShift, Tony Hawk’s Pro Skater, True Crime, Zork, and probably a few others I missed.