These planets in habitable zone (or more %)
Fragment of a discussion from Comments:715 exoplanets discovered by Kepler telescope
If we did, it's a very well-kept secret.
However, not necessarily a good indicator. Look at the evolution of our use of the electromagnetic spectrum for communications; we're less that 100 years from the first transmissions that might be detectable across interstellar space; we've refined our use of such communications to be more-directed, less broadcast; and, we're switching to encryption which will just look like "background noise".
Brian McNeil / talk