  Within the statistical model, the net strangeness conservation and incomplete
total strangeness equilibration lead to the suppression of strange particle
multiplicities. Furthermore, suppression effects appear to be stronger in small
systems. By treating the production of strangeness within the canonical
ensemble formulation we developed a simple model which allows to predict the
excitation function of $K^+/\pi^+$ ratio in nucleus-nucleus collisions. In
doing so we assumed that different values of $K^+/\pi^+$, measured in p+p and
Pb+Pb interactions at the same collision energy per nucleon, are driven by the
finite size effects only. These predictions may serve as a baseline for
experimental results from NA61/SHINE at the CERN SPS and the future CBM
experiment at FAIR.
