An electronic Raman scattering study at low frequency has been performed on YBa₂Cu₃O₇ single crystals below and above the transition temperature T_c. The intensity of the electronic continuum at low frequency shows a drastic change with temperature variation. The differential cross section calculation based on the Green's function formalism in the random-phase approximation has permitted us to isolate the low-energy electronic contribution from the phonons and point out its behaviour as a function of temperature. A decrease of the electronic contribution in the superconducting state compared with that in the normal state then appears, which it is possible to assign to the pairing of the free carriers near the Fermi energy. However, this low-energy electronic contribution persists well below T_c, suggesting the existence of electronic states near the Fermi energy even in the superconducting state.