72t - whats the percent that can be taken out?

[retiringat50]

I understand with 72t one would need to either take the same amount of money out every year for 5 yrs or until one reaches 59.5 (whatever is longest). Just read that there is a % from last years retirement fund that can be taken.

What is that %?

and id still be able to dip in if I find its not enough, right