The current qualifying system was adopted in the 2006 season. Known as "knock-out" qualifying, it is split into three periods, known as Q1, Q2, and Q3. In each period, drivers run qualifying laps to attempt to advance to the next period, with the slowest drivers being "knocked out" of qualification (but not necessarily the race) at the end of the period and their grid positions set within the rearmost five based on their best lap times. Drivers are allowed as many laps as they wish within each period. After each period, all times are reset, and only a driver's fastest lap in that period (barring infractions) counts. Any timed lap started before the end of that period may be completed, and will count toward that driver's placement. The number of cars eliminated in each period is dependent on the total number of cars entered into the championship. Currently, with 20 cars, Q1 runs for 18 minutes, and eliminates the slowest five drivers. During this period, any driver whose best lap takes longer than 107% of the fastest time in Q1 will not be allowed to start the race without permission from the stewards. Otherwise, all drivers proceed to the race albeit in the worst starting positions. This rule does not affect drivers in Q2 or Q3. In Q2, the 15 remaining drivers have 15 minutes to set one of the ten fastest times and proceed to the next period. Finally, Q3 lasts 12 minutes and sees the remaining ten drivers decide the first ten grid positions. At the beginning of the 2016 Formula 1 season, the FIA introduced a new qualifying format, whereby drivers were knocked out every 90 seconds after a certain amount of time had passed in each session. The aim was to mix up grid positions for the race, but due to unpopularity the FIA reverted to the above qualifying format for the Chinese GP, after running the format for only two races.