The quote from B.Bodhi:
AB: Bhante, I had another speculative question, which I was going to leave out, but since we’ve now brought it up … Saṁsāra is considered to be without beginning, without discoverable beginning. So in theory there would have been an innumerable number of Buddhas in the past. If there have been an innumerable number of Buddhas, but there is only a finite number of beings, then why isn’t everybody enlightened already? How come we’re still here?
BB: Perhaps consciousnesses can emerge.
BB: In infinite time, if you sat a large numbers of monkeys at computers typing away, they are bound to type the Majjhima Nikāya. (laughs)
Link: Interview with Bhikkhu Bodhi
There is no way to solve this problem by ourselves if we are not statistical geniuses. We can try to reinvent the wheel by ourselves but that might not work. This is why we should use google as often as possible when having a difficult question, especially in the complicated field of statistics.