New measurements are presented for charged hadron azimuthal correlations at midrapidity in Au+Au collisions at √s_NN=62:4 and 200 GeV. They are compared to earlier measurements obtained at √s_NN=130 GeVand in Pb+Pb collisions at √s_NN=17:2 GeV . Sizeable anisotropies are observed with centrality and transverse momentum (pτ) dependence characteristic of elliptic flow (v₂). For a broad range of centralities, the observed magnitudes and trends of the differential anisotropy,v₂ (pτ), change very little over the collision energy range √s_NN=62–200 GeV, indicating saturation of the excitation function for v₂ at these energies. Such a saturation may be indicative of the dominance of a very soft equation of state for √s_NN ~ 60–200 GeV.