Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Season | Series | Team | Races | wins | Poles | Fast laps | Points | Pos. |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 2001 | Formula One | Prost | Test driver | Test driver | Test driver | Test driver | Test driver | Test driver |
| 2001 | Formula 3000 International | GD Racing | 4 | 0 | 0 | 0 | 0 | NC |
| 2001 | World Series by Nissan | GD Racing | 6 | 0 | 0 | 1 | 51 | 9th |
| 2002 | World Series by Nissan | GD Racing | 6 | 0 | 0 | 0 | 30 | 13th |
| 2003 | World Series by Nissan | GD Racing | 2 | 0 | 0 | 0 | 0 | NC |
| 2006 | Formula One | Renault | Test driver | Test driver | Test driver | Test driver | Test driver | Test driver |
| 2007–08 | A1 Grand Prix | A1 Team France | 2 | 0 | 0 | 0 | 0 | 4th |
Question:
which season held the most series?
Answer:
2001