It is worth observing that one should distinguish between two vision types:
photopic and
scotopic.
In these two different "states" of the eye the spectral response changes. It would be useful to know to which state the above curve and data refer.
Anyway, in scotopic vision the rod cells are engaged, and the eye becomes more sensitive to short wavelenghts, that's to say the peak shifts towards blue (the rods peak at 500 nm)