Detection of Neptune-size planetary candidates with CoRoT data. Comparison with the planet occurrence rate derived from Kepler by Bonomo, A, Chabaud, P, Deleuil, M, Moutou, C, Bouchy, F, Cabrera, J, Lanza, A, Mazeh, T, Aigrain, S, Alonso, R, Guterman, P, Santerne, A, Schneider, J