System-size dependence of strangeness production in high-energy A+A collisions and percolation of strings

We argue that the shape of the system-size dependence of strangeness production in nucleus-nucleus collisions can be understood in a picture that is based on the formation of clusters of overlapping strings. A string percolation model combined with a statistical description of the hadronization yields a quantitative agreement with the data at $sqrt{s_{NN}}=17.3$ GeV. The model is also applied to RHIC energies.