Hmm that's an interesting way to think of it. At 0.16%, assuming uniform distribution of detectable aliens and none detected in that range, that would estimate an upper bound of 625 alien species in the milky way. That does feel kind of lonely.
That would be 625 species with radio technology at approximately the same level as ours. Presumably as technology progresses, their transmitters and receivers improve whereas the distance over which they communicate stays relatively constant and thus their output power should decrease. It's also possible a more advanced civilization uses other communication methods, for example optical fiber might render satellite communications totally obsolete.
Further the 0.16% is the fraction of the galactic disk area, not stars. Also note that the 0.16% is the region we could sweep with a theoretical telescope that we might be able to build in the near future, not the region we've actually surveyed thus far.
