All statistical calculations of this type type related to evolution are nonsense on stilts.
Probabalistic calculations can only be applied in one of two cases:
1: When
all the events in the chain are random and unconnected to each other. The classic example of this is in throwing a coin. The result of one throw does not affect another: regardless of the number of heads in a run, the probability of throwing a head remains 0.5. However, the probability of certain results for a number of throws can be calculated exactly.
2: When all the possible paths and their likelihood is known. This can only be done
ex post facto. In this case you can analyse a
past event and state the odds of having achieved the percieved event.
Neither holds for evolution.
Evolutionary events are
not isolated - one event influences the possible sequence of future events, therefore statistical analysis is impossible.
The number of
possible events is unknowable - therefore the probabilities cannot be calculated after the event.
Performing such calculations as are common on creationists sittes is a sure sign of mathematical illiteracy.
The only statistical figure that can be derived for life is that the probability of life on Earth is 1.