<p>You may be able to get a hint of the distinction you want by looking at the difference between freshman and all undergrads numbers. Often freshmen are not allowed to live off-campus except if living with their parents, or if non-traditional students. So for most schools the number of off-campus freshmen may be a decent representation of the percent of “commuter” students overall, and a drop in the percent of on-campus students overall probably represents students moving to a nearby off-campus apartment.</p>