I'm pretty sure this is unknown, though it would be great if I'm wrong.
Asymptotically there is a function $A(n)$ such that $M(n,n/2+t)\sim e^{-2t^2}A(n)$ for $t=o(n^{1/2})$, which follows from this paper.
It is also known to be true for $n\le 20$.