As Peter said, the local percentile is for kids in that district only. There are plenty of bright kids in our district, and many you would not suspect are really bright. Our district doesn't use the Cogat, but I have seen the national and our HS percentiles for the SAT. My eldest had a 97th percentile score nationally on the math section of the SAT, but it was only 83rd percentile for her HS. The average SAT three part score for her class would rank 80th percentile nationally.
Unfortunately, when you have a lot of bright kids, you need to make the cut somewhere. In my eldest's class, they were still letting kids into the gifted program through recommendations, outside testing, etc. in early elementary. Now I understand that most or all of those kids probably benefit from the gifted program, but almost 25 percent of the class was labeled gifted. The district now chooses the IQ test, administers it and requires a 130+ (no GAI allowed either).