The hardest part is deciding what exactly it is you want to know. The way you phrased the question is really vague. Are we talking about a typical speedsolve by a typical sub-15 cuber? Linear fewest moves? FMC? Optimally one substep at a time with no look-ahead? Optimally everything at once?
Fridrich F2L and EOLine are fairly clear, but the substeps of ZZ F2L need to be defined. I personally use many ad-hoc techniques after EOLine.
Getting approximate (or sometimes exact) averages using a computer simulation is easy if you can formulate the question clearly (remember that computers can't think and don't understand what they're doing). The results you get may or may not have any correlation with human solutions, however, so think carefully before drawing any conclusions.