The space between two hollow concentric spheres of radii $0.1\:m$ and $0.2\:m$ is under vacuum. Exchange of radiation (uniform in all directions) occurs only between the outer surfaces $(S_{1})$ of the smaller sphere and the inner surface $(S_{2})$ of the larger sphere. The fraction (rounded off to the second decimal place) of the radiation energy leaving $S_{2}$, which reaches $S_{1}$ is _______________