Distribution of the ratios of the \piz\ meson masses found by a fit in the narrow interval ($\mu^{\text{fit}}_n$) of $70 <\mu_\pi^{0} < 220$ MeV/$c^2$ with respect to the standard range ($\mu^{\text{fit}}_s$) of $50 <\mu_\pi^{0} < 300$ MeV/$c^2$, for cells located behind the zones with more material (filled distribution) and for the other cells (blue distributions) for \glspl{SM} 0--17. The latter histogram is fit with a Gaussian (red).