When a compressor pumps one CFM (cubic foot per minute), that means the intake port inhales one cubic foot of free air (air at atmospheric pressure, which is 0 psig) per minute. (Note: A CFM does not mean in any sense the compressed volume.) So the unit really measures the mass of air flowing per minute, not volume per minute, since a cubic foot of free air is a unit of mass.
This second scale has a mean and standard deviation that have been arbitrarily set. A z score, for example, is a raw score that has been transformed to a scale with a mean of 0 and a standard deviation of 1.
Here is a screencast showing how to produce a score conversion chart using Excel. The main way to convert a z score to a percentile is to use NORMSDIST*100. If you wish to convert a T or SS (Standard Score) or ss (Scaled Score) to a percentile, without first converting to a z score, use NORMDIST*100. In the screencast, the mean values for each scaled score is entered first (i.e., 0, 100, 10, 50).