Antti entered a 10-kilometer race. His goal is to finish in one hour. He starts off sprinting and completes the first 2 kilometers of the race at an average speed of 12 kilometers per hour. To achieve his goal of a one-hour finish time, what average speed (in kilometers per hour) must Antti maintain for the last 8 kilometers of the race? Enter your answer as a number in decimal form, without units.