80%

Originally posted by Shallow Blue
We've looked at the electromagnetic output from thousands of sources - millions, if you count SETI@Home. Not one of them showed the kind of pattern you would expect from an intelligent broadcast. At least, not one of them showed the kind of pattern you would get from our kind of intelligence. On that count, at least, we are exceptional.
Now, of ...[text shortened]... ife there, or anywhere. There's life here. That's exceptional, right there.

Richard

The main reason why we would not detect radio etc. signals is because the "intelligent" source is too far away and we cannot distinguish it from noise and natural sources.