the entire time.
jokes aside, I'd guesstimate about 3 years.
Joker : Let's wind the clocks back a year. These cops and lawyers wouldn't dare cross any of you. I mean, what happened? Did your balls drop off? Hmm? You see, a guy like me...
Mobster 1 : A freak.
Joker : A guy like me... Look, listen. I know why you choose to have your little, ahem...group-therapy sessions in broad daylight. I know why you're afraid to go out at night. The Batman. See, Batman has shown Gotham your true colors, unfortunately. Dent, he's just the beginning. And as for the television's so-called plan...Batman has no jurisdiction. He'll find him and make him squeal. I know the squealers when I see them...and...