  The measured K$^+/\pi^+$ ratios from heavy-ion reactions are compared with
the K$^+/\pi^+$ ratios from p+p reactions over the energy range 2-160 AGeV. The
K/$\pi$ enhancement in heavy-ion reactions is largest at the lower energies,
consistent with strangeness production in secondary scattering becoming
relatively more important than initial collisions near the kaon production
threshold. The enhancement decreases steadily from 4 to 160 AGeV, suggesting
that the same enhancement mechanism of hadronic rescattering and decay of
strings may be applicable over this full energy range. Based on existing data,
the mid-rapidity K$^+/\pi^+$ ratio is predicted to be $0.27\pm0.05$ for the
forthcoming Pb+Pb reactions at 40 AGeV/c.
