Using average values in the drake equation, there have been have been 18 million broadcastable civilizations in the milky way. If we take an average lifespan o

Using average values in the drake equation, there have been have been 18 million broadcastable civilizations in the milky way. If we take an average lifespan of 1,000 years and say those cilizations have formed over the last 5 billion years (where planets mostly cooled down throghout the universe) then there are currently only 4-5 broadcastable civilizations in the milky way. Is that correct?