For much of the sport's history, qualifying sessions differed little from practice sessions; drivers would have one or more sessions in which to set their fastest time, with the grid order determined by each driver's best single lap, with the fastest on pole position. Grids were generally limited to 26 cars – if the race had more entries, qualification would also decide which drivers would start the race. During the early 1990s, the number of entries was so high that the worst-performing teams had to enter a pre-qualifying session, with the fastest cars allowed through to the main qualifying session. The qualifying format began to change in the early 2000s, with the FIA experimenting with limiting the number of laps, determining the aggregate time over two sessions, and allowing each driver only one qualifying lap.