2014. For the Ninja 1000 that's a 4th gen, 2014-2016. The 3rd gen Ninjas were 2010-2013 if memory serves, though they might go back a bit further. The '17 and up are the 5th gens, and it was the '20 and up that got all the major changes. The '17-'19 was just body work, lights, and some other small changes, but the frame and suspension was untouched, so far as I can tell.
EDIT : I had almost forgotten, I did measure the fork tubes before installing them, and there was no difference, so I doubt the lower clamp changed. I'll measure again later today to verify. I suspect the Z1K saw some major changes well before the N1K.