At Amazon, the target was between 4 to 6% when I was there, but it was applied at the larger department level, not individual teams. It was perfectly fine to have a team of 10 where nobody was on a PIP (yes, such things exist!), but when it came to my entire 250-person department, all of the managers were in a room together ranking every employee they had and using "data" (peer reviews and results delivered, mainly) to fight over which employees got into the top and bottom tiers.