Answer:
As given by you yourself, 50, zero.
Project SETI has been ongoing for about 50 years and has so far communicated with zero other civilizations.
Step-by-step explanation:
Strangely enough, nobody agrees when SETI started it seems? Wikipedia says 1999, seti.org says 1984, history.nasa.gov says 1959 - 1960... so that year number is veryyyy uncertain!