The percentage basically represents the portion of all CT4 or CT5 allocations (including non V-series) that are available for ordering that week. So 0% means that 0 allocations were given that week for the entire country, 5% would represent a maximum of 5% of the total allocations for that week, and so on. So if your dealer has 2 CT5 allocations this week, with a 5% constraint, that's 0.1 car, which basically means zero Blackwings. If the same dealer has 20 CT5 allocations, they might get 1 Blackwing. It gets a bit more complex than that, but you get the gist. This info comes from the constraints report which is distributed to dealers as a PDF every Thursday, so any dealer that has any clue about ordering cars should be able to pull up this info for you in about 30 seconds!