There seems to be lots of threads started about number of bottoms and tops in a population, seemingly drawing different numbers from different people given their experience and their location.

Under the assumption that it is rare to find two tops or two bottoms in a relationship together perhaps due to rather unmatched sexual preference, I'm just curious as to the prevalence of top/bottom, vers/vers relationships between two men in a population. And, one step further, if anyone can, what are the prevalence of open/closed relationships for m2m relationship within a population.