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:
| Pos | No | Driver | Team | Laps | Time/Retired | Grid | Points |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 14 | Robert Doornbos | Minardi Team USA | 107 | 1:45:07.617 | 15 | 31 |
| 2 | 21 | Neel Jani | PKV Racing | 107 | +6.1 secs | 5 | 27 |
| 3 | 3 | Oriol Servià | Forsythe Racing | 107 | +6.9 secs | 4 | 26 |
| 4 | 5 | Will Power | Team Australia | 107 | +7.5 secs | 12 | 23 |
| 5 | 1 | Sébastien Bourdais | N/H/L Racing | 107 | +8.0 secs | 2 | 21 |
| 6 | 2 | Graham Rahal | N/H/L Racing | 107 | +9.6 secs | 6 | 19 |
| 7 | 19 | Bruno Junqueira | Dale Coyne Racing | 107 | +14.0 secs | 10 | 17 |
| 8 | 22 | Tristan Gommendy | PKV Racing | 107 | +19.2 secs | 8 | 15 |
| 9 | 42 | Jan Heylen | Conquest Racing | 107 | +28.5 secs | 13 | 13 |
| 10 | 15 | Simon Pagenaud | Team Australia | 107 | +48.4 secs* | 9 | 11 |
| 11 | 3 | Paul Tracy | Forsythe Championship Racing | 105 | + 2 Laps | 11 | 10 |
| 12 | 28 | Mario Domínguez | Pacific Coast Motorsports | 104 | + 3 Laps | 14 | 12 |
| 13 | 22 | Justin Wilson | RSPORTS | 87 | + 20 Laps | 1 | 8 |
| 14 | 29 | Alex Figge | Pacific Coast Motorsports | 34 | Contact | 0 | 7 |
| 15 | 11 | Alex Tagliani | RSPORTS | 83 | Mechanical | 8 | 6 |
| 16 | 11 | Katherine Legge | Dale Coyne Racing | 13 | Contact | 16 | 5 |
| 17 | 4 | Dan Clarke | Minardi Team USA | 3 | Contact | 3 | 4 |
Question:
what was the number of drivers that did not finish the race?
Answer:
4