I'd say Witcher 3 was a little below or on par with Mass Effect, Fable, Dragon Age, Elder Scrolls, Fallout or a Final Fantasy offering and combined you likely see at least one of those a year on average.
The only way I could imagine saying that is if you focus only on the mechanics of the RPG game loop and ignore world design, dialog quality, voice acting, characters, breadth of content, quests, etc.