Thanks for the info, futbol. Your surprise comparing what was available for you versus the unused list is understandable. You were there the day before, so what was available was only the permits returned by the few good people who go to the trouble to go online and actually cancel their reservation. The overnight permit no-shows are only declared the date of the entry, at 10 AM.
If you had asked how many were available that morning for starting THAT day, the numbers would have been quite a bit higher.
