conversion mahalanobis distance (multivariate distributions) to percentage

hi,

i have data that would return vertex points of shape (coordinate x and y) example A x1,y1), (x2,y2), (x3,y3), (x4,y4),(x1,y1), (x2,y2) and group B: (x5,y5),(x6,y6). my data group would have two group, A group (39 coordinates) and group B (4 coordinates).

i applied mahalanobis distance to calculate the dissimilarity computation and mahalanobis distance return standard deviation results from expected data.

how im going to get the percentage of the mahalanobis distance and what method is better use for my data? now i already trying statistical normalization (z-score):

but my problem is, im getting confuse to place the input data for X, u and standard deviation based on my data:(. really appreciate for any ideas since im really urgent to know this. Anyway thank you for the great site

thanks

aznimah