Electron energy-loss spectra covering the elastic and inelastic region up to 15.0 eV were obtained at 20, 30, and 200 eV impact energies at scattering angles ranging from 8° to 130°. Relative differential elastic scattering cross sections were determined at each impact energy and then, normalized to the absolute scale by utilizing the 100° differential cross sections of Tanaka et al. (private communication) at 20 and 30 eV and to theory [Dahl et al. J. Phys. B 12, 2727 (1979)] at 200 eV. The inelastic region of the energy-loss spectrum was divided into five ranges. From the integrated scattering intensities over these ranges with respect to the elastic scattering and from the normalized elastic cross section, the inelastic cross sections were calculated.