If you place all channellers of similar strength in buckets, you'll get the bell curve that Maria was talking about. Meaning, the majority will fall into the top three most occupied buckets, with weirdos, for example Rand and Ishy, occupying the outmost bucket.

If you place all channelers in buckets with pre-assigned absolute value of strength (let's say arbitrary number from 1 to 100, or from 1 to 21), it may not be a bell curve. It may be that majority of channelers will occupy the lower 1/3 part of distribution, or the higher 1/3 part.

Additional stuff,
When you look at channelers distribution and try to assign power strength based on the index of the bucket, it may also be invalid to call it power distribution after that.
The reason is that there could be a great jump in power between let’s say “Narishma” and Rand. But since there are no channelers in between, there is no bucket that separates them and it may confuse people that “Narishma” is so close in power to Rand when in fact he is not.