Before revision:  When we focus on the probability distribution of cancellation positions at a certain price level, we find that the PDF increases rapidly in the front of the queue, and then fluctuates around a constat value until the end of the queue.
After revision:  When focusing on the order cancellation positions in the queue at each price level, we find that the PDF increases rapidly in the front of the queue, and then fluctuates around a constat value until the end of the queue.